In the jewelry industry, they are known as the “four C’s”: Carat, Color, Clarity, and Cut. But a word, Humpty told Alice, can mean whatever the speaker wants it to. But once you know what these words are supposed to mean, you can judge for yourself whether someone offering loose diamonds for sale online is being honest with you, or Humptying around. Briefly, all of the “four C’s” describe one thing: rarity.
In ancient times, the carob seed was used to weigh precious gems, gold, silver or platinum. The diamond was placed in one pan of the scale, and carob seeds were placed in the other pan until it balanced. Each seed was called a “carat”. By the 1900s, however, the carob seeds and two-pan scales were obsolete, so a carat was standardized for jewelers at 1/5 of a gram, and each carat was subdivided into 100 “points”. So a half-carat diamond weighs 50 points, or 0.10 grams. This standard remains, whether among professional merchants, or on web sites offering loose diamonds for sale online.
Only one in a million diamonds unearthed can be successfully cut into a one-carat polished stone. But only one in three million can be cut into a two-carat stone. Thus, two-carat diamonds are three times as rare as one-carats, and therefore three times as expensive.
Mixed in with the crystals are traces of the materials that surrounded them while they changed from coal into diamonds. Some of these trace elements will give a diamond a light tint, usually yellow, but often blue, red or other more exotic hues.
The Gemology Institute of America (GIA) grades diamond color on a scale from D to Z, D being colorless and Z being yellow. Anything above Z on the GIA scale is referred to as “fancy” colored. As previously mentioned, rarity is the key to evaluating diamonds. So the most valuable diamonds are either as close as possible to colorless, or are fancy. The most popular diamonds range from D to J, or from colorless to nearly colorless, and the price goes up about 10 to 15% for each GIA grade.
Trace elements can also cause internal flaws, called “inclusions,” including specks, cloudy areas, or “feathering”. The GIA also grades for clarity, ranging from FL (Flawless), IF (Internally Flawless), VVS 1 and 2 (Very Very Slightly Included), VS 1 and 2 (Very Slightly Included), SI 1 and 2 (Slightly Included) to I 1-3 (Included). These flaws are not visible to the naked eye until the SI2 grade. Those graded higher have flaws seen under a 10X magnification, and only experts can distinguish the finer grades. But the higher the grading is, the rarer the gem, thus more valuable.
A diamond will have 57 facets, 58 if you count the cullet. It has five parts:
1. the table (flat top);
2. the crown (embellishments around the table but above the girdle);
3. the girdle (setting edge);
4. the pavilion; and
5. the cullet (pointy bottom, which can be flattened to avoid chipping).
The pavilion must be formed at the proper depth, so that light passing through the diamond will be refracted and reflected back up to increase the brilliance of the set, polished gem.
Cuts are graded as Ideal, Excellent, or merely Very Good.
Let the Buyer be aware
When comparing loose diamonds for sale online, all four C factors must be considered in order. Fortunately, GIA has a grading system, provided for each gem.