As diamond brokers, JPratt Designs offers hundreds of loose stones, including certified diamonds, to suit your taste and budget. The following is a list of criteria, commonly referred to as “The 4-Cs”, by which a diamond is graded:

The 4-Cs – cut, clarity, color and carat weight – are the characteristics that determine a diamonds rarity and value – and as a result, its price. No two diamonds are alike, although they may sometimes look identical to the naked eye. The 4-Cs, and the many ways in which they can be combined, are the key to understanding why two diamonds of equal size may not be of equal value. A basic understanding of each classification is important in making an informed purchase.

When looking to purchase a diamond, strive for a stone that offers a combination of the 4-Cs which best match your goals. Also, since beauty is in the eye of the beholder – don’t be afraid to use your eyes and trust your heart in selecting the diamond that speaks most to you. A basic understanding of the 4-Cs will help you to select the diamond that’s perfect for you.

Gems

The traditional gemstones are rubies, emeralds and sapphires. Because of their lasting appeal and distinguished history, ruby, emerald and sapphire are more valuable than other colored gemstones. Generally, rubies and emeralds are also priced higher than a comparable quality sapphire due to rarity. For a one-carat stone of average to good quality in the varieties in this category, you can expect to pay between $250 and $10,000 per carat. Of course truly fine gems will cost more.

In every variety, especially the more expensive ones, you should expect to pay more for matched pairs, sets, and special shapes and cuts.

Value factors: Color, Clarity, Cut and Carat Weight. Gemstone quality and value are evaluated according to the four C’s.

Color is the key factor. A common mis-perception in judging gems is people assume that the darker the color, the better the stone. That isn’t true: color can be too dark, like some sapphires that look more black than blue. If a gem’s color is too dark, it is subdued and lifeless. A much better rule of thumb is the brighter and more rich and vivid the color the better. In general, within each gemstone variety, a clear, medium-tone, very intense and saturated primary color is the most preferred. Muted colors or colors between hues, which you might find very attractive, are usually less expensive. Look at the color in different kinds of light.

The next most important factor affecting value is clarity, with clear transparent gemstones with no visible flaws being the most valued. Some gemstone varieties, notably emerald and red tourmaline, are very rare without inclusions of some kind so the price structure takes this into account.

Some gemstones are valued for their inclusions! Phenomenal gemstones owe their stars and eyes to inclusions. Tiny inclusions reflecting back light put the eye in cat’s-eye chrysoberyl and the star in star sapphire. Inclusions can also be a birthmark, telling us where a particular gemstone was mined.

A good cut is something that may not cost more but can add or subtract a lot of beauty. A well-cut faceted gemstone reflects light back evenly across its surface area when held face up. If the stone is too deep and narrow, areas will be dark. If it is too shallow and wide, parts of the stone will be washed out and lifeless. The best way to judge cut is to look at similar gemstones next to each other. Ask your jeweler to show you a well-cut gemstone.

Gemstones are generally sold by weight not by size. The price will be per carat, which is one-fifth of a gram. Some gems are heavier than others so the same weight stone may be a different size! The carat weight also affects the price: large gemstones are more rare, so the price per carat is higher.

In general, gemstone pricing within each variety follows common sense: the more beautiful the gemstone, with the final visual effect of all the quality factors, the more valuable it is. Don’t be afraid to choose what looks best to you!

Taken from the International Colored Gemstones Association.