Pts. system of measurement?

[iori]

Just been looking looking at sq. collets in the catalogue, for 4mm. stones,but they appear to be measured in "pts". Would someone kindly explain what pts are and their relationship (if any) to mms. Thanks.
Yours,
Iori

[Goldsmith]

I am not sure about Cookson's catalogue collet sizing but I would guess that the "pts" refers to the term points, which is the divisions of a carat in stone weights, there are 100 points to a carat. Checking my records a 4mm square princess cut diamond weighs approx. 30 points or 0.30ct. If I am correct then the square collets that
are sized at 25pts may be OK for 4mm square stones. But I would advice that you check with someone before ordering. There are other suppliers who quote mm sizes for their collets.
James

[iori]

Thank you James for throwing light on this. Doesn"t seem very logical to me basing the size of the collet on the weight of the stone, since the size is going to vary with the specific gravity of the stone. Some history or tradition attached to this I guess! Thanks again.
iori

[ps_bond]

I think it may be related to the idea that the only stone worth mentioning is a diamond, while everything else is just "coloured stones" - so why specify for anything else?

As a complete phillistine, I rather like coloured stones. Particularly with silver.