Ratti vs Carat: The Gemstone Weight Confusion, Solved

Published by Tushar Gems & Jewellery Pvt. Ltd. — Gurugram & Delhi | Natural · Certified · Trusted | Since 1998

Your astrologer says 5 ratti. The seller quotes a price for 5 carats. You assume you are talking about the same stone. You are not — and the difference can be thousands of rupees.

This is the most common confusion at a gemstone counter in India, and it takes two minutes to clear up for good.

Two units, one stone

Carat is the international unit of gem weight. One carat is exactly 200 milligrams, or 0.20 grams. Every laboratory report in the world states weight in carats.

Ratti is the traditional Indian unit used in astrology, originally based on the seed of the gunja (ratti) plant. Astrologers prescribe in ratti; the trade weighs in carats.

Neither is "more accurate". They are simply two scales for the same thing, the way kilograms and pounds are.

The conversion

• 1 ratti ≈ 0.91 carat
• 1 carat ≈ 1.10 ratti
• To go from carat to ratti: carat × 1.10
• To go from ratti to carat: ratti × 0.91

A small note on precision: the ratti has historically varied slightly from region to region, which is why you will see figures like 0.90 or 0.91 carat quoted. For buying purposes the difference is minor — what matters is that both sides know which unit is being used.

Where buyers lose money

Because 1 ratti is less than 1 carat, quoting the same number in the wrong unit always works in the seller's favour.

If you ask for a 5 ratti Pukhraj and are handed a 5 carat stone priced as "5", you have paid for roughly 10% more weight than you needed. On a fine untreated stone, 10% is a significant sum — and your astrologer did not ask for it.

The fix is one sentence at the counter: "Is that five ratti or five carat?"

Reading your certificate

Laboratory reports state carats, almost always to two decimal places — for example 4.55 ct. If a seller's bill says ratti but the certificate says carat, convert and check they agree. The weight on the report is the weight you are buying.

Watch for two other things:

• Weight of the stone, not the ring. Gross weight including metal is a different number entirely.
• Price per carat vs total price. Coloured stones are usually priced per carat, and that per-carat rate rises steeply as size increases.

Why bigger is not automatically better

The prescribed weight comes from your chart. Tradition holds that a stone lighter than advised may be ineffective — but there is no tradition that says more carats bring more benefit. Extra weight beyond the recommendation is simply extra cost.

It also affects the ring: a much heavier stone changes the setting, the metal weight and how the piece sits on the finger.

A quick worked example

Your astrologer advises a 6 ratti Neelam.

1. 6 × 0.91 = 5.46 carat — this is what you ask for
2. Seller quotes a rate per carat, so the total = rate × 5.46
3. The certificate should read close to 5.46 ct
4. If you are offered a 6.00 ct stone instead, you are buying about half a ratti more than advised — fine if you want it, but know that you are choosing it

Frequently asked questions

Is ratti an official unit?
Not in the international trade. Laboratories and the global market work in carats; ratti survives because astrological prescriptions are traditionally given in it.

My stone weighs slightly less than prescribed. Is that a problem?
Small variation is normal, since stones are cut to their own natural shape. Ask your astrologer what range is acceptable.

Does ratti mean the same for every stone?
The unit is the same, but the same weight looks different across stones — emerald is lighter than sapphire, so a 5 carat emerald looks bigger on the hand than a 5 carat sapphire.

Can I convert at home?
Yes. Multiply ratti by 0.91 for carats, or carats by 1.10 for ratti.

We quote both, every time

At our counters we tell you the weight in both units and show you the certificate before anything is billed. Bring your astrologer's note and we will match it exactly — no rounding up in our favour.

Tushar Gems & Jewellery Pvt. Ltd.
Gurugram: Shop No. 19–20, 2nd Floor, Gold Souk Mall, Sushant Lok 1, Sector 43, Gurugram, Haryana 122009 — open all seven days, 11 AM–8 PM
Delhi: 36/3092 Beadon Pura, Karol Bagh, New Delhi 110005 — Tuesday to Sunday, 11 AM–8 PM
Phone & WhatsApp: +91 95400 05349 · tushargems2026@gmail.com
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Disclaimer: Gemstone recommendations described in this article are based on traditional Vedic astrology and are shared for informational purposes. They are not a substitute for medical, financial or legal advice.