Convert Ratti to troy ounces

From seed to standard

Seed-based weights were once used across the subcontinent because the gunja seed is unusually consistent in mass. Consistent is not the same as exact, however, and the historical spread between individual seeds is large enough that no seed-based system could ever settle a gold contract. The modern ratti is therefore a defined fraction — eight ratti to the masha, ninety-six to the tola — rather than a botanical measurement.

This matters when reading older gemmological literature, which sometimes quotes a "ratti" close to the carat instead. That value comes from a separate jeweller convention, not from the tola-derived ladder used here, and the two should never be mixed inside one calculation.

Country context: gemstones and astrology

Astrological prescription is the main living use. A jyotish recommendation is typically written as a minimum ratti weight for a specific stone, and dealers in Jaipur, Delhi, Karachi and Kathmandu price accordingly. Because the recommendation is a floor rather than a target, buyers frequently pay for the excess above the prescribed weight, which makes the exact conversion commercially relevant rather than ceremonial.

International gem trade, by contrast, works entirely in metric carats. Any stone crossing that boundary — an imported sapphire sold on a ratti prescription, or an Indian stone certified abroad — is converted at least once, and certificates should always carry the metric weight as the authoritative figure.

Ratti versus carat

The metric carat is exactly 0.2 g by international agreement. The tola-derived ratti is a different quantity entirely, so a stone described as "5 ratti" is not five carats, and treating the two as interchangeable misstates the weight substantially in either direction depending on which local convention the seller used.

Where a document does not say which ratti is meant, the honest reading is to record both interpretations and ask. This atlas uses the tola-derived value consistently so that the ratti, masha and tola on this site always reconcile to the same underlying anchor.

Practical guidance for buyers and appraisers

Anyone buying an astrological stone should ask for three numbers rather than one: the weight in ratti as prescribed, the same weight in metric carats, and the convention the dealer used to move between them. A seller who cannot answer the third question is quoting a number they have not checked, and that is the point at which the buyer is exposed.

Appraisers face the mirror problem. An heirloom described only in ratti has to be re-weighed before it can be valued, because the documented weight cannot be trusted to a convention nobody recorded. The re-weighed metric figure becomes the authoritative record and the ratti figure is kept as provenance, not as data.

For datasets, the rule is the same one that applies throughout this atlas: store the metric value, keep the traditional value as a labelled string, and never let the traditional figure become the source of truth. Once a ratti weight is converted and stored as a number, the convention behind it is lost and cannot be recovered from the file.

Common mistakes to avoid

• A ratti is not a carat; the two are unrelated definitions and confusing them misprices gemstones.
• Some dealers use a "jeweller ratti" close to 0.2 g — always confirm which convention a quoted weight follows.
• Eight ratti make a masha; multiplying by ten is a frequent slip in converted inventories.
• Certificates should quote metric carats or grams; a ratti-only certificate is not internationally verifiable.