|When you tell people one diamond weighs more than another, they usually understand what you mean, but few consumers realize how precisely diamonds are weighed. Like most gems, diamonds are weighed in metric carats; one carat equal 0.2 grams, a little more than 0.007 (seven thousandths) ounce avoirdupois (this is the same type of ounce used to measure produce in the grocery store; precious metals are weighed in troy ounces). In other words, it takes little over 142 carats to equal 1 ounce. |
But even this is not precise enough for something so precious. Even with relatively inexpensive diamonds, fractions of a carat can represent hundreds of dollars (thousands, with top quality stones). For this reason, in the diamond industry, weight is measured to a thousandth of a carat and rounded to the nearest hundredth or point.
The largest gem diamond ever recorded, the Cullinan, weighed 3,106.75 carats (just over 21.9 ounces) in the rough. The biggest gem cut from the Cullinan rough weighed 530.20 carats; it is the second largest fashioned diamond in the world. Every few years, miners bring a new giant to light: seven of the ten largest diamonds known have been discovered in the twentieth century (three since 1970).
The weights of diamonds used in jewelry range from less than a point to more than 100 carats, but the majority are between 5 points and one carat. Diamonds weighing less than 20 points are called melee (rhymes with belly).
Loose diamonds can be weighed on a jeweler’s balance. With mounted diamonds, however, weight must be estimated by measuring the stone using a weight-estimation formula. Estimating weight is less precise than direct weighing, but close enough to allow appraisers to make reasonable evaluations without unmounting the stones.
As weight increases, so does price but, since larger stones are more rare, greater weight also increases price-per-carat. For example, a rough crystal that will yield a four-carat stone is much more rare than rough that yields a one-carat stone, so a cutter must pay a higher per-carat-price for the larger crystal. This means the total price for four one-carat diamonds will be considerably less than the price for a single four-carat diamond of comparable quality.
Based on this, choosing the best size for you would depend on many factors: namely the finger size, the style and setting desired and finally, your budget.
If size is an important factor for you or the one you are getting it for, less emphasis can be placed on the other Cs to choose a larger diamond.
A 1 to 3-carat diamond that may be perfect for an average finger size appears too small for a larger finger size and may look too big for a smaller finger size.
Also some styles and settings may be able to fit diamonds only in a certain range of carat weights. They may also make diamonds appear larger or smaller than they really are.
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