Why the same gemstone may have two weight numbers
An adviser may recommend a gemstone in ratti while a shop or laboratory report states carats. Those numbers cannot be compared safely without knowing the conversion convention being used. Start with a measured metric weight, ask what the seller means by ratti, and keep weight separate from size, quality and astrological suitability.
The most useful question is not “Which number sounds larger?” but “What does this stone weigh in a clearly defined unit, and what am I paying for?”
One metric carat is 0.2 grams
A metric carat is exactly 200 milligrams, or 0.2 grams. It is a weight unit for gemstones. Karat, used in descriptions such as 18-karat gold, refers to gold purity and is a different concept. GIA’s diamond carat-weight explanation describes the metric unit; the unit itself also applies to coloured gemstones.
This gives you a dependable conversion without needing a gemstone-specific chart. Multiply carats by 0.2 to get grams, or divide grams by 0.2 to get carats. A 3-carat stone weighs 0.6 grams, a 4-carat stone weighs 0.8 grams, and a 5-carat stone weighs 1 gram. These are weight calculations, not recommendations about which stone a person should wear.
Why ratti needs clarification
Ratti is a traditional unit encountered in Indian gemstone trade and guidance. Published trade conversion guides do not all use the same convention. An online converter may produce a precise-looking number while leaving its assumption unstated. That precision does not establish which definition your seller or adviser intended.
For example, this commercial ratti conversion discussion illustrates the need to clarify usage; it is not a universal standard or an endorsement of that seller. Rather than copy a single conversion into every purchase, ask how many milligrams or carats are meant by one ratti in your quotation.
How to check a conversion without guessing
Write down the stone’s measured carat weight first. Then ask the seller for their stated ratti conversion factor and its units. If their convention is expressed as carats per ratti, divide the measured carats by that factor to obtain ratti under that convention. If it is expressed as grams per ratti, convert the stone’s weight into grams before dividing.
Label any result with the convention used. Do not silently mix a converter’s factor with a seller’s factor. If an astrologer prescribed a ratti weight, confirm the intended definition with that adviser rather than assume a search result settles it. Converting units does not establish that a gemstone is appropriate for your chart.
Weight is not face-up size
Two stones of equal carat weight may look different in size because mineral density, cut and proportions differ. A deep cut can retain weight beneath the visible surface. Ask for length, width and depth in millimetres as well as carats, particularly if the gemstone needs to fit a setting.
Compare gemstones of the same species and similar proportions when judging visible size. A larger-looking stone is not automatically more valuable or better suited to wear. Colour, transparency, treatment and condition remain part of the decision.
Compare price on the same basis
A per-carat rate and a whole-stone price are different quotations. For an illustrative example, a 4-carat stone at ₹1,000 per carat has a stone subtotal of ₹4,000 before any additional disclosed charges. This arithmetic example is not a current price quotation or an assurance about availability.
If one seller quotes per ratti and another per carat, ask both for the total stone price and measured carat weight before comparing. Lower price per unit alone says nothing about mineral identity, treatment or quality. Certificate options and setting costs should also be stated separately so you know the final amount.
What to ask before checkout
- What is the measured carat weight of this exact stone?
- What are its dimensions in millimetres?
- If ratti is quoted, which conversion convention is being used?
- Is the price per carat, per ratti or for the whole stone?
- What treatment information and laboratory documentation accompany it?
Read our gemstone lab-report guide before checking documents, then browse the GemJyotish collection to compare clearly labelled stone weights and current quotations. For chart-related questions, seek guidance separately from the arithmetic: a unit conversion cannot guarantee an astrological result.
