What Size Gemstone for Your Body Weight, and Who Benefits From a Bigger One

The rule, and how much it varies

The convention is body weight in kilograms divided by ten to twelve, read as ratti. At 60 kg that gives 5 to 6 ratti. At 80 kg, 6.7 to 8.

Divisors differ by lineage. Some use ten, some twelve, some ignore body weight and work from a fixed minimum per planet. The rule is a trade convention of modern gemstone practice rather than a formula set out in the classical literature, which is worth knowing when it is presented as ancient.

What most traditions agree on is a floor rather than a target: below roughly three ratti a stone is generally considered too small to be worth setting for this purpose. That is a much smaller claim than the sizing table, and a more defensible one.

There are two ratti, and they differ by half

This is the part that costs people money.

The pakki ratti, the one used for astrological gemstones, is 182.25 mg. The sunari or goldsmith ratti is 121.5 mg. The pakki is exactly 1.5 times the sunari, so the same number means two very different stones depending on which the seller is using.

Against the metric carat, which is exactly 200 mg, one pakki ratti is about 0.91 carat and one sunari ratti about 0.61. A 5 pakki ratti stone is roughly 4.55 carat. A 5 sunari ratti stone is about 3.04.

The ratti derives from the seed of Abrus precatorius, and the historical figure sat near 0.1215 g, which is where the sunari value comes from. Ask which ratti a quote uses before comparing prices.

Weight to size, at both common divisors

The table gives both ends of the usual range so you can see how wide the disagreement is. Treat it as the span you are likely to be quoted, not as a calculation with a right answer.

Why this rule gets quoted so often

Price does not rise in a straight line with size. Larger clean stones are rarer, so twice the weight costs well more than twice as much.

That makes body weight the most profitable rule in the room: it sounds precise and it only ever points upward. If a recommendation exceeds the table, ask which divisor and which ratti are being used.

There is no evidence a heavier stone works better, and the tradition claims no dose-response relationship. When to be suspicious of remedy advice covers the rest of the patterns.

Size is the last question, not the first

Size matters only after the stone is right, and that is decided by your chart, not your weight. Which planet to strengthen depends on your ascendant and the houses that planet rules for you, which is why the same gemstone suits one person and is advised against for another.

Work through which gemstone your chart actually points to first. If the answer is blue sapphire, read who should wear it and who should not before spending anything, because that is the one stone the tradition itself treats with caution. Then, and only then, is body weight worth a conversation.