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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 and Carat Guide 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 and Carat Guide.
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 practical cautions belong here.
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 seeds contain the toxic substance abrin. Do not swallow them, use them as a home remedy or give them to children as toys. Suspected ingestion needs prompt medical attention. Their historical use as counterweights does not make them safe.
For a modern purchase, use a calibrated scale rather than 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. The metric carat is a defined 200 mg unit, rather than a different local convention in each market. Ask which unit and measurement the particular report or seller records.
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, establishing the 200 mg metric value. The metric carat should be distinguished from older regional carat conventions.
Ratti quotations still require the seller to state a convention. Checking that basis is more useful than assuming that every ratti quotation means the same mass.
| Unit | Value | Status |
|---|---|---|
| Metric carat (ct) | Exactly 200 mg = 0.2 g | The metric carat has a defined 200 mg value; check the unit stated on the actual report |
| 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
There is more than one ratti convention in Indian trade. The two discussed here are 121.5 mg and 182.25 mg; the larger is one and a half times the smaller.
The kacchi ratti — also called the sunari ratti, the goldsmith's ratti — is about 121.5 mg. In the traditional gold-weighing ladder, 8 ratti make a masha and 12 masha make a tola, so 96 ratti make a tola. Taking the tola as 11.6638 grams gives 11.6638 ÷ 96 ≈ 0.1215 g, or about 121.5 mg. This explains the arithmetic of the convention; internal consistency alone does not establish which historical usage is older.
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 a common convention in astrological gemstone quotations, but ask the practitioner and seller which weight they mean.
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; historical values differed between places such as Madras, Bombay and Bengal. Using the standard grain of 64.79891 mg, 1.75–1.8 grains is approximately 113.398–116.638 mg, not 0.1215 g. Conversely, 0.1215 g is approximately 1.875 grains. Keep these conventions separate when comparing historical weight references.
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 = 0.91125 carat ≈ 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 | A common shorthand in retail and conversion guides |
| 121.5 mg (kacchi / goldsmith's) | ≈ 0.608 ct | ≈ 1.646 ratti | Associated with gold work; ask the seller rather than assuming the intended gemstone convention |
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: the 182.25 mg pakki unit is 50% heavier than the 121.5 mg kacchi unit; conversely, the kacchi unit is one-third lighter. A ratti quotation without a stated basis is not enough for a reliable comparison.
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 static weight guide explains
Our Ratti and Carat Guide 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.
This is a static explanation, not an interactive calculator. It does not impose one authoritative ratti conversion. A calculation using 180 mg or 182.25 mg is only useful when that is the seller’s stated convention; first confirm 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 static guide to check the carat, gram and ratti basis on any listing before comparing weights.
Open the Ratti and Carat Guide →Tola, masha, ratti: the ladder Indian jewellers still climb
The ratti forms part of a traditional weight ladder used in gold trade: 8 kacchi ratti make a masha and 12 masha make a tola. These two steps use different multipliers, not a purely base-12 system.
| 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.
Accounts using 100 ratti seeds and a ladder using 96 ratti should not be treated as identical measurements. The 96 figure follows from 8 ratti to a masha and 12 masha to a tola, and gives about 121.5 mg when a tola is 11.6638 g. A seed-count account may use another convention; without a specific source, it should not be explained simply as rounding.
One further point worth stating plainly. India's own legal framework runs on the metric system. Section 4 of the Legal Metrology Act, 2009 establishes a metric basis for weight and measure. The detailed treatment of units belongs to the applicable rules, rather than a general claim that every customary unit is interchangeable. For a gemstone purchase, ask the seller for the mass in carats or grams and the ratti convention used, and check the units on the invoice and report.
Primary references: CDC: abrin and seed safety; 1907 CGPM proceedings: metric carat; Legal Metrology Act, section 4: metric basis. Check the actual report and applicable rules for a particular transaction. NIST Handbook 44: grain conversion.
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. Values such as 3.25, 5.25, 7.25 and 9.25 ratti appear in recommendations. Do not assume the quarter fraction is a universal classical requirement; ask which named text or teaching supports a recommendation. Ratti also functions as familiar trade vocabulary: “a five-ratti Pukhraj” may evoke the appearance of a set stone, while “0.91 grams” expresses its mass.
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
A report can record a measured weight in a stated unit. Check the issuer, the scope of testing and whether the document corresponds to the actual stone. The table explains common report fields; not every report includes every field or test.
| Line on the report | What it means |
|---|---|
| Weight | Often expressed in carats, sometimes with a gram equivalent. Read the actual unit and precision; do not assume every document uses the same format. Ask for a metric mass if only a customary unit is shown. |
| 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 | May disclose heat treatment, fracture filling, oiling, diffusion or irradiation, depending on the laboratory and report scope. Some reports classify treatment or its degree; ask what was tested and what limitations apply rather than assuming an omitted line means untreated. |
| 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 | Check the report number and date against the issuing laboratory’s record where a lookup is available. A matching record alone does not prove that the stone in hand is the reported item; also compare its weight, dimensions and identifiers, and seek clarification if they differ. |
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 from a gemmological laboratory. Depending on its scope, it may state identification, natural or synthetic status, weight, dimensions, treatment findings or origin. Read the actual tests and limitations rather than assuming every document covers all of them.
A government laboratory certification describes who issued a document, not a single universal test or report type. A government laboratory may issue a gemstone report. For any Divine Hindu item, check the selected listing and the actual document’s issuer, item reference and test scope . Do not assume that every Karungali item has the same report or that “government certified” automatically establishes a gemstone’s origin, treatment status or quality. Ask for the document and read precisely what it covers.
A report describes findings within its test scope. It does not certify a spiritual, health or financial outcome.
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. Compare the material, condition, treatment information, dimensions and weight together; a target number alone does not establish quality or suitability.
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 commonly taken as about 121.5 milligrams, within the ladder of 8 ratti to a masha and 12 masha to a tola. The pakki convention discussed here is 182.25 milligrams, one and a half times as much: 50 percent heavier than kacchi. Conversely, kacchi is one-third lighter than pakki. Pakki is a common gemstone convention, but confirm the actual basis with the seller.
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?
Section 4 of India’s Legal Metrology Act, 2009 establishes a metric basis for weight and measure; detailed unit provisions are in the applicable rules. Tola and ratti remain customary trade expressions. For a gemstone purchase, request the mass in carats or grams, ask which ratti convention was used and check the actual units on the invoice and report.
Does the Divine Hindu weight guide provide an interactive converter or a fixed ratti value?
No. It is a static guide explaining that a metric carat equals 200 milligrams or 0.2 grams, with a reference to the Gemological Institute of America. For ratti quotations, ask the seller for the mass in carats or grams and the convention used for that item. A conversion factor is meaningful only when its assumed ratti value is stated.
What does a gem lab certificate actually certify?
A gem laboratory report records findings within its stated scope. These may include weight, dimensions, material identification, natural or synthetic status, treatments and, for some stones and report types, geographic origin. It does not certify a promised outcome. Check the issuer’s report record where available, then compare the item’s measurements and identifiers; an online record alone does not prove the physical stone matches.
Is a gem lab certificate the same as government certification?
The terms are not interchangeable: one describes a gemmological report, while the other describes an issuing authority. A government laboratory can issue a gemstone report. Check the issuer, the specific item and the tests covered. For Divine Hindu products, consult the selected listing and actual document; do not assume blanket certification for every gemstone or Karungali item.
Visit us or shop online
For gemstones and their listed specifications, check the selected item’s available report and 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 and Carat Guide · Choosing Gemstone Weight · Kundli Milan: The 36 Gunas
