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TL;DR — A metric carat is exactly 200 milligrams. That number is fixed by international agreement and does not vary. The ratti is not fixed in the same way: it began as the weight of a single Abrus precatorius seed and was never standardised across India. The two values you will meet most often are the goldsmith's or kacchi ratti at about 121.5 mg and the pakki ratti used for astrological gemstones at about 182.25 mg — which is why one seller's "5 ratti" can be a noticeably different stone from another's. Using the pakki ratti, 1 ratti ≈ 0.91 carat and 1 carat ≈ 1.10 ratti; sellers who round the ratti to 180 mg get 0.90 and 1.11 instead. The safe habit is simple: ask for the weight in carats or grams, and treat the ratti figure as a label rather than a measurement. Our Ratti Carat Converter page walks you through exactly that check.
If you have ever shopped for an astrological gemstone in India, you have run into this. One shop quotes a Pukhraj at "5.25 ratti". Another quotes what looks like the same stone at "4.75 carat". A third gives you grams. A lab certificate arrives with a fourth number on it. None of them obviously agree, and the natural suspicion is that somebody is being clever with the arithmetic.
Usually nobody is. The problem is older and duller than that: the ratti was never a single, standardised unit, and the carat is. Two honest sellers using two honest traditions will produce two different numbers for the same stone. This guide covers the ratti and its origin in a seed, the metric carat and why it is the reliable half of the pair, why published conversion factors differ, the tola–masha–ratti ladder, and how to read the weight line on a gem lab certificate — written to be used alongside our Ratti Carat Converter.
What a ratti actually is
The ratti — rattika or raktika in Sanskrit, from rakta, red — is the seed of Abrus precatorius, the plant called gunja in Sanskrit, chirmi or ratti in Hindi, gulaganji in Kannada and kunrimani in Tamil. The seed is small, hard, glossy and unmistakable: scarlet over about three-quarters of its surface with a sharp black cap at the hilum end. It is the seed that gets strung into tourist jewellery and, historically, the seed that Indian goldsmiths kept in a small box on the counter and used as a counterweight on a balance.
Why a seed? Because for most of history there was no better option. A balance is only as good as the weight on the other pan, and small, uniform, durable objects that could be replaced anywhere beat a machined brass weight that had to be trusted and transported. Traders across the ancient world reached the same solution independently — which is the direct link to the carat.
Two honest caveats belong here, and most articles on this subject leave them out.
The seeds are not as uniform as the tradition believed. The old claim that gunja seeds are all but identical in weight is part of the folklore of the trade, and modern measurement does not fully support it: like most seeds they show real variation between plants, regions and seasons. The tradition was working with a good approximation, not a physical constant. This matters, because the entire premise of the ratti is a seed that always weighs the same, and that premise is only roughly true.
The seed is poisonous. Abrus precatorius contains abrin and is genuinely toxic if the seed coat is broken and the seed is swallowed. Intact seeds passed through the trade for centuries without incident because nobody ate them, but they are not something to give a child to play with, and they are not a remedy of any kind. They are a measuring weight, and that is the whole of their role here.
Today no reputable dealer weighs a sapphire against actual seeds. The ratti survives as a number — a customary unit jewellers, jyotish practitioners and their clients still speak in — long after the object it named went out of use. That is exactly the situation in which a unit drifts.
The metric carat: the fixed half of the pair
One metric carat = 200 milligrams = 0.2 grams. Exactly. Not approximately, not by convention in some markets and not others. It is a defined value, and every gem laboratory, every customs authority and every trade body in the world uses the same one.
The carat has almost the same origin story as the ratti. The word comes through Italian and Arabic from the Greek keration, the seed of the carob tree (Ceratonia siliqua), used as a counterweight by Mediterranean and Arab traders for the same practical reasons Indian jewellers used gunja. And it drifted exactly as the ratti drifted: before standardisation, regional carats across Europe and the Levant ranged from roughly 188 mg to 213 mg, so a parcel bought by carat in one city and sold by carat in another could gain or lose several per cent without anyone cheating.
The difference is that the carat got fixed. The metric carat of exactly 200 mg was adopted by the Fourth General Conference on Weights and Measures in 1907, and was written into national law in the major gem-trading countries over the following years. From that point the carat stopped being a customary unit and became a metric one — 200 mg, defined, universal.
The ratti never had its 1907. That single historical fact is the source of essentially every ratti-versus-carat argument you will ever have with a seller.
| Unit | Value | Status |
|---|---|---|
| Metric carat (ct) | Exactly 200 mg = 0.2 g | Defined by international agreement since 1907; used on every gem lab certificate |
| Gram (g) | 5 carats | SI unit; what Indian legal metrology is built on |
| Point | 1/100 carat = 2 mg | Trade shorthand — "a 75-pointer" is 0.75 ct |
| Ratti (pakki / gemstone) | Commonly taken as ~182.25 mg; often rounded to 180 mg | Customary. No single legal definition; usage varies by seller and region |
| Ratti (kacchi / sunari, goldsmith's) | ~121.5 mg | Customary. One-eighth of a masha in the tola ladder |
| Masha | 8 ratti (kacchi) ≈ 0.972 g | Customary; still spoken in the gold trade |
| Tola | 12 masha = 96 ratti ≈ 11.6638 g | Customary; standardised in the colonial period as exactly 180 troy grains |
Kacchi and pakki: the two rattis, and why your number moved
Here is the single most useful thing in this article. There is not one ratti in circulation in India. There are at least two, and they differ by half again.
The kacchi ratti — also called the sunari ratti, the goldsmith's ratti — is about 121.5 mg. This is the ratti that sits inside the traditional gold-weighing ladder: 8 ratti make a masha, 12 masha make a tola, so 96 ratti make a tola. Since the tola was standardised at 11.6638 grams, a little arithmetic gives 11.6638 ÷ 96 = 0.1215 g, or 121.5 mg. The system is internally consistent, which is a good sign that this value is the older and more structural of the two.
The pakki ratti — the one used for astrological gemstones — is conventionally one and a half times the kacchi ratti: 1.5 × 121.5 mg = 182.25 mg. This is the ratti a jyotish practitioner almost always means when recommending a stone, and the one most gem dealers use when they quote in ratti.
So when a customer says the jeweller gave them something much smaller than the astrologer's "five ratti" led them to expect, the usual explanation is that the two were not speaking the same unit. Five pakki ratti is about 911 mg; five kacchi ratti is about 608 mg. That is not rounding — it is a different stone at a different price.
Older sources record a further layer: the ratti was regionally variable long before the kacchi–pakki split, with Madras, Bombay and Bengal each working to different values. Reference works give the historic standardised ratti as roughly 1.75 to 1.8 grains, around 0.1215 g — but that was a standardisation imposed on genuinely varied practice, not a description of universal usage.
The conversion, and why published factors disagree
Now we can do the arithmetic honestly.
Take the pakki ratti at 182.25 mg. A carat is 200 mg. So:
- 1 ratti = 182.25 ÷ 200 = 0.911 carat, usually quoted as 0.91 ct.
- 1 carat = 200 ÷ 182.25 = 1.0974 ratti, usually quoted as 1.10 ratti.
Now take the same pakki ratti rounded to a flat 180 mg, which a great many Indian dealers and websites do:
- 1 ratti = 180 ÷ 200 = 0.90 carat.
- 1 carat = 200 ÷ 180 = 1.111 ratti, quoted as 1.11 ratti.
That is the whole mystery. You will see 0.90 and you will see 0.91; you will see 1.10 and you will see 1.11. Both pairs are defensible. They are not competing claims about a fact of nature — they are two roundings of a customary unit that has no defined value to round.
| If a source assumes 1 ratti = | Then 1 ratti in carats | Then 1 carat in ratti | Where you will see it |
|---|---|---|---|
| 182.25 mg (1.5 × kacchi ratti) | 0.911 ct | 1.097 ratti | Dealers who derive the pakki ratti from the tola ladder |
| 180 mg (rounded) | 0.90 ct | 1.111 ratti | The commonest shorthand in Indian retail and on conversion websites |
| 121.5 mg (kacchi / goldsmith's) | 0.608 ct | 1.646 ratti | Gold work; almost never intended for gemstones, but does get quoted by mistake |
How much does the 180-versus-182.25 choice matter? Less than people fear. On a 5-carat stone the two factors give 5.56 and 5.49 ratti — about 0.07 ratti apart, well inside what a jeweller would call the same stone. The difference that matters is kacchi versus pakki, which is 50%, and worse still is a seller quoting ratti with no stated basis at all.
A practical rule you can do in your head
For everyday shopping, ratti and carat are close enough that you can treat them as roughly one-to-one and then correct by about a tenth. A stone described as 5 ratti is somewhere near 4.5 carats. A stone described as 5 carats is somewhere near 5.5 ratti. If a seller's ratti figure is more than about 10–12% away from that, something else is going on — either they are using the kacchi ratti, or the number is not a conversion at all but a nominal size.
What our converter page does, and what it deliberately does not do
Our Ratti Carat Converter page is short, and it is short on purpose. It does three things. It states that one metric carat equals 200 milligrams, or 0.2 grams, and links to the Gemological Institute of America's explanation of carat weight as the reference. It reminds you that carat measures weight, so it has to be read alongside the stone's dimensions and other listed specifications — two stones of identical carat weight can look very different sizes depending on cut and species. And it tells you what to do about a weight quoted in ratti: ask the seller to state the weight in carats or grams, and to explain which ratti measure they used for that product.
What the page does not do is publish a single authoritative ratti-to-carat number and invite you to trust it. A converter that silently picks 180 mg, or silently picks 182.25 mg, presents a customary unit as though it were a defined one, and will confidently give a wrong answer whenever the seller picked the other value. The honest tool sends you back to the seller for the basis.
If you are checking a Divine Hindu item and the listing does not make the weight clear, contact our team with the product link and the weight shown and we will confirm it. You can also browse the specifications on individual listings in our gemstone collection and the wider all gemstones range.
Check a weight before you compare two listings
Use the converter page to work through the carat, gram and ratti figures on any listing — ours or anyone else's.
Open the Ratti Carat Converter →Tola, masha, ratti: the ladder Indian jewellers still climb
The ratti does not stand alone. It is the bottom rung of a base-12 ladder that Indian and Pakistani jewellers still use daily, mostly for gold rather than gemstones.
| Step | Relationship | Approximate metric value |
|---|---|---|
| 1 ratti (kacchi) | The base unit | ≈ 0.1215 g (121.5 mg) |
| 1 masha | 8 ratti | ≈ 0.972 g |
| 1 tola | 12 masha = 96 ratti | ≈ 11.6638 g |
The tola is the rung most people have heard of, because gold is still priced and discussed per tola in Delhi, Lahore and Karachi, and because the old British India one-tola silver and gold bars are still traded. Its standardised value of 11.6638 grams comes from its colonial-period definition as exactly 180 troy grains — tidy in imperial, untidy in metric.
You will sometimes hear that a tola was "the weight of 100 ratti seeds", and you will also see the arithmetic above giving 96. Both statements circulate. The 96 figure is the one that is internally consistent with 8 ratti to the masha and 12 masha to the tola, and it is the one that reproduces the 121.5 mg ratti; the 100 figure looks like a rounded description of the same idea. This is another small illustration of the same theme — the traditional system is coherent in its own terms but was described loosely for a long time before anyone tried to pin it to grams.
One further point worth stating plainly. India's own legal framework runs on the metric system. The Legal Metrology Act, 2009 requires units of weight and measure used in trade to be metric, based on the International System of Units, with the carat given specific accommodation as a weight used in the gem and bullion trade. Tola and ratti persist as customary usage in the market; they are not the units the law is written around. That is not a reason to distrust a seller who speaks in ratti — practically everyone in the Indian gem trade does — but it is a good reason to make sure the number that ends up on your invoice and your certificate is in carats or grams.
Why jyotish practitioners and Indian jewellers still quote in ratti
Given all of the above, a reasonable question is why the trade does not simply drop the ratti. Several reasons, and none of them is dishonesty.
The recommendations are inherited in ratti. When a jyotish practitioner suggests a weight, they are usually working from a rule of thumb or a teacher's instruction that was itself expressed in ratti, and many prefer to hand the number on in the form they received it. And the customer speaks ratti: the ratti figure is the one they can check against what they were told.
Ratti numbers have customary shapes. Recommendations cluster on values like 3.25, 5.25, 7.25 and 9.25 ratti — the quarter is conventional, and round numbers are widely avoided. These are habits of the trade rather than requirements of any classical text. The ratti is also a size language as much as a weight language: "a five-ratti Pukhraj" evokes a picture of the set stone for most Indian buyers in the way "0.91 grams" does not.
The reasonable position, and the one we take, is that there is nothing wrong with speaking ratti as long as everybody knows it is a customary label and the binding number on the paperwork is metric.
How to read a gem lab certificate
The weight on a gem laboratory certificate is the number to trust, because it is the one measured on a calibrated balance and expressed in a defined unit. Here is what the lines on a typical report mean, and what a certificate does and does not tell you.
| Line on the report | What it means |
|---|---|
| Weight | Given in carats, usually to two decimal places, sometimes with the gram equivalent. This is the authoritative figure. It will not be in ratti. |
| Dimensions | Length × width × depth in millimetres. Read this alongside the weight — a deep-cut stone carries weight you cannot see from the top. |
| Identification / Species | What the stone is: "natural sapphire", "natural emerald (beryl)" and so on. Also whether it is natural, synthetic (lab-grown) or an imitation. This is the single most important line on the page. |
| Variety | The trade name within the species — "blue sapphire", "yellow sapphire" — both of which are corundum. |
| Comments / Treatment | Whether the stone has been heat treated, fracture filled, oiled, diffused or irradiated. Laboratories are expected to detect and disclose these. Some report a simple treated/untreated; others grade the degree, as GIA does for clarity enhancement in emerald (None, Minor, Moderate, Significant). |
| Origin | Geographic source, offered only by some laboratories and only for some stones where origin affects value. Its absence is normal and is not a defect in the report. |
| Report number and date | Lets you verify the report against the laboratory's own database. Do this. It is the only way to know the certificate belongs to the stone in your hand. |
An important distinction: gem lab certificate versus government certification
These two phrases get used interchangeably in the Indian market and they are not the same thing at all. It is worth being precise, because the conflation misleads buyers.
A gem laboratory certificate is a technical report issued by a gemmological laboratory on a specific stone. It identifies the species, states whether the material is natural or synthetic, records weight and dimensions, and discloses detectable treatments. It is a factual description of that one stone.
A government laboratory certification is a different instrument entirely, issued for a different purpose. At Divine Hindu, government laboratory certification applies to our Karungali (Ebony) products only — it is not a claim we make about gemstones. Our gemstones are sold with their own gem lab documentation where that documentation exists, and you should read that documentation for what it says: species, natural or synthetic, weight, treatment. Anyone who tells you a coloured stone is "government certified" is either talking about something else or is being loose with language, and it is a fair question to ask them to clarify.
A certificate certifies material facts. It does not certify that a stone will do anything.
Practical checks before you buy
- Get the weight in carats or grams. Ratti is fine as a conversation; carats belong on the invoice.
- If a ratti figure is quoted, ask which ratti. "Is that on 180 milligrams or 182.25?" is a completely normal trade question and a serious seller will answer it without hesitation.
- Compare like with like. Convert both listings to carats before comparing prices. A price per ratti is comparable only if both sellers use the same ratti.
- Read the dimensions, not only the weight. Carat is mass; two 5-carat stones of different species or cuts can differ visibly in face-up size.
- Verify the certificate number with the laboratory, and look for the treatment line. Its absence is a question, not an answer.
- Do not let weight decide the purchase on its own. The classical emphasis in the tradition is on the quality of the material rather than on hitting a number.
Where to go next
If your next question is "how many ratti should I actually wear", that is a separate conversation with its own traditions and its own caveats, and we have written it up in Choosing Gemstone Weight: What Tradition Says and How to Convert It. If you are earlier in the process and still working out which stone the tradition associates with your chart, start with the rashi stone chart for all twelve signs, the navratna guide to the nine gems, or shop by rashi. To understand where a stone recommendation comes from in the first place, see How to Read Your Kundli.
For stone-by-stone detail, see our guides to Pukhraj (yellow sapphire), Neelam (blue sapphire), Panna (emerald) and Manik and Moti (ruby and pearl). Practical wearing customs are in which finger to wear which gemstone.
Frequently Asked Questions
How many carats is 1 ratti?
Using the pakki ratti of about 182.25 milligrams, which is the measure normally intended for astrological gemstones, 1 ratti is about 0.911 carat, usually quoted as 0.91 carat. Sellers who round the ratti to a flat 180 milligrams get 0.90 carat instead. Both figures are in common use because the ratti has no single standardised value, so always ask the seller which basis they used and get the final weight stated in carats or grams.
How many ratti is 1 carat?
One carat is about 1.10 ratti if the ratti is taken as 182.25 milligrams, and about 1.11 ratti if the ratti is rounded to 180 milligrams. A metric carat is exactly 200 milligrams, so the arithmetic is simply 200 divided by whichever ratti value the seller uses. The difference between 1.10 and 1.11 is small in practice, but it is a real difference in assumption rather than an error by either party.
Why do different websites give different ratti to carat conversions?
Because the ratti was never standardised in the way the carat was. The metric carat was fixed at exactly 200 milligrams by the Fourth General Conference on Weights and Measures in 1907 and has one value everywhere. The ratti began as the weight of an Abrus precatorius seed, varied regionally across India, and survives today in at least two forms: the goldsmith's or kacchi ratti of about 121.5 milligrams and the pakki ratti of about 182.25 milligrams used for gemstones. Different sources pick different values and round them differently.
What is the difference between kacchi ratti and pakki ratti?
The kacchi or sunari ratti is the goldsmith's ratti of about 121.5 milligrams, which sits inside the traditional ladder of 8 ratti to a masha and 12 masha to a tola. The pakki ratti, used for astrological gemstones, is conventionally one and a half times that, about 182.25 milligrams. The two differ by 50 percent, so a stone quoted in the wrong one will be substantially larger or smaller than expected. When a gemstone is quoted in ratti, the pakki ratti is almost always what is meant.
What is a metric carat?
A metric carat is exactly 200 milligrams, or 0.2 grams, and five carats make one gram. It was adopted by the Fourth General Conference on Weights and Measures in 1907 to replace the regional carats then in use, which ranged from roughly 188 to 213 milligrams. It is now used by gem laboratories, jewellers and customs authorities worldwide. Carat measures weight rather than size, so it should be read alongside a stone's millimetre dimensions.
Is ratti the same as tola or masha?
No, they are different rungs of the same traditional ladder. Eight kacchi ratti make one masha of about 0.972 grams, and twelve masha make one tola of about 11.6638 grams, so 96 ratti make a tola. The tola is standardised at 11.6638 grams because it was defined in the colonial period as exactly 180 troy grains. Tola and masha are mostly used for gold in the Indian and Pakistani trade rather than for gemstones.
Is ratti a legal unit of measurement in India?
India's Legal Metrology Act, 2009 requires units used in trade to follow the metric system based on the International System of Units, with the carat given specific accommodation as a weight used in the gem and bullion trade. Tola and ratti continue as customary units in the market and are widely spoken by jewellers and jyotish practitioners, but they are not the units the law is framed around. For that reason it is sensible to make sure the weight on your invoice and certificate is stated in carats or grams.
Does the Divine Hindu converter page give a fixed ratti to carat number?
No, and that is deliberate. The Ratti Carat Converter page states the one figure that is genuinely fixed, that a metric carat is 200 milligrams or 0.2 grams, and cites the Gemological Institute of America for carat weight. For a weight quoted in ratti it asks you to have the seller state the weight in carats or grams and explain which ratti measure they used for that product. Publishing a single conversion factor would present a customary unit as though it had a defined value.
What does a gem lab certificate actually certify?
A gem laboratory certificate records measurable facts about one specific stone: its weight in carats, its dimensions in millimetres, its identification as a species, whether it is natural, synthetic or an imitation, and any detectable treatments such as heat treatment, fracture filling, oiling, diffusion or irradiation. Some laboratories also give geographic origin for certain stones. It does not certify that a stone will produce any outcome, and it should always be verified against the issuing laboratory's report number.
Is a gem lab certificate the same as government certification?
No. A gem laboratory certificate is a technical report on a single stone issued by a gemmological laboratory. Government laboratory certification is a different instrument, and at Divine Hindu it applies to our Karungali (Ebony) products only. It is not a claim we make about gemstones. If a seller describes a coloured stone as government certified, it is reasonable to ask exactly which document they mean and what it states.
Visit us or shop online
For certified gemstones with their specifications stated on each listing, browse our gemstone collection and gemstone jewellery, or visit Divine Hindu Store, Jayanagar 3rd Block East, Bengaluru 560011. If a weight on any listing is unclear, contact our team with the product link. Related reading: Ratti Carat Converter · Choosing Gemstone Weight · Kundli Milan: The 36 Gunas
