Carat

[jbenning]

As a rank amature in the diamond market, and assuming a fairly ideal cut and proportions, how much variance in carat do you think is detectable by eye? Could a lay person detect a .9 vs a .95, or a .9 vs a 1.0? What does everyone think?

 

[phoenixgirl]

Usually not, especially considering that many one carat stones are cut deep to hit that magic 1.00 carat target. Thus, a majority of one carat stones have the diameter of a smaller stone with correct proportions. Since people have seen those deep cut stones and been told they're one carat, they would probably assume a 0.95 is too. Plus we're talking about tenths of a millimeter, if that.

 

[valeria101]

There is a tradeoff between the total depth of the stone and diameter. For each 1% of added depth one looses some percentage of diameter. Withing the the range of ideal cuts (59%-61%) there is room for 0.1cts to be "compensated for" byt depth variaces alone. The larger the size of diamond, the more weight each % of depth "absorbs"... (the usual statement says that the diameter or size of round diamonds incresses less and less with each added carat). So a 0.9 and a 1ct may have the same diameter, even if both can be called "ideal".

Some say that o.1mm diference is visible. I guess they mean it is "when comparing diamonds side by side".... What is "visible " seems to be better expressed in % of the face-up surface of the stone. I guess 10% is already obvious relative to the finger, even if the stones are not compared side by side (but alternatively placed against the finger, as I would procede to do this).

just my 0.2... of course.