Gail: Divide the weight in grams by 15. 15 grains equals 1 gram.
You can get a grain scale at a gun shop where bullet reloading
equipment is sold.
I would like to offer a caution in using this value, as it will
produce a 2.88% error in calculation!
Actually, 1 “grain” = 64.79891 milligrams, or = .0647981 grams,
which is 15.43255 grains to the gram. Didn’t really mean to be a
"nit picker" (American expression), but sometimes that "little"
insignificant error (2.88%) can hurt you.
A 25 carat gem on a grain scale would weigh 77.16 grains. Converting
77.16 grains to carats using 15 grains to the gram would yield 5.144
grams, or 25.72 carats. If I was buying that gem, I would be
overpaying for 0.72 carats. Depending on the cost per carat, this
may be trivial, or an expensive error!
An extra tidbit here - this kind of fits in with the discussion going
on about units of measurements. While most measurement systems have
their origin based on the trades or scientific research, their
ultimate usage usually comes down to commerce of one sort or another,
although, of course, not always. While your background may cause you
to prefer one measurement system over another, you can usually
convert from one to the other. Your “quartz” wrist watch is a
product of science and keeps fabulous time due to scientific pursuit
of greater accuracy. Greater accuracy usually requires better
resolution. Greater resolution allows us “facetors” to cut with
better uniformity, even though our skill level is below that of a
My apology for rambling so over such a, perhaps to some, trivial
matter. By training, schooling, and experience I am an Engineer,
Metrologist (art and science of measurements) and an amateur facetor.
I can contribute little to the Arts - I suppose I am to
"structured". I can, however suggest different ways to look at use
of measuring tools and units, etc.
To all, have a nice day, and again, my apology for being so wordy.
John Trautmann; firstname.lastname@example.org