Not many people may know that carats do not mean the same for diamonds and gold. For gold, it is a measure of purity, on the other hand, in diamonds it's a weight measure.

The size of a diamond has the biggest impact on its price. The metric carat, which equals 0.20 gram, is the standard unit of weight for diamonds and most other gems.

If other factors are equal, the more a stone weighs, the more valuable it will be. Gemological laboratories measure carat weight when the diamond is loose (unmounted).

In today's world if the diamond is over one carat in size it will usually come with a certificate from the laboratory specifying the inclusions, color and size. The carat itself is made of one hundred particular parts called points.

While it is possible to estimate the weight of a mounted diamond, the lab uses ultrasensitive scales to achieve an exact weight, measured 3 decimal places, although the third decimal place is not usually mentioned at the retail level.

Here are several ways to express 1 carat: 1 ct.

200 milligrams
1/5 gram
100 points
4 grainer (not often used in retail environment)

That's why a 2 carat diamond is more than double the price of a 1 carat diamond.

The Beauty of round diamond

The best cut will display the diamond's brilliance to the best effect. When looking at a stone you need to look from the top down, this way you can see all of the facets and you need to check to see if you can see any inclusions in the diamond.

Teardrop diamond is known as pear and the emerald cut is an octagonal shape which is oblong, the marquise diamond is an oval and it has points at the end. But, the pavilion can be cut with 4, 6, or 8 pavilion main facets. There are so many different types of cuts, there is the round, square, pear and cushion. When a diamond is cut it is cut for brilliance and to let the light reflect off of the facets.

There are many shapes of stones, but the one shape that is most sought after is the round diamond, it has the greatest reflective power and brilliance. The brilliance is determined by the ability of the diamond to reflect light.

The transparent white colorless diamond is most popular variety, but diamond also occurs in colors. When color is prominent it is called a fancy diamond. There are many different factors that will create color in a diamond. One of those factors is carbon spots in the diamond itself which will through off the color.

Any diamond ring can make a good anniversary present. The solitaire is another ring that people like to give as an anniversary present. Most people notice the engagement ring and not the wedding band. That's why most women will want a nice round diamond of at least 1 carat in size. It is usually the engagement ring that is admired, not her wedding ring. And the setting of the diamond solitaire is there really just to hold the diamond.

Platinum is fast becoming the favorite choice in diamond settings and bands. When platinum is used for jewelry it is sometimes used for its strength and high shine and the ability to resist scratching. Platinum is geared toward a more modern look, whereas gold is traditionally beautiful.

Carat for gold

The carat (abbreviation ct or Kt) is a measure of the purity of gold alloys. In the United States and Canada, the spelling karat is used, while the spelling carat is used to refer to the measure of mass for gemstones).

Therefore 24-carat gold is fine (99.9 per cent Au w/w), 18-carat gold is 75 per cent gold, 12-carat gold is 50 per cent gold, and so forth.

Historically, in England the carat was divisible into four grains, and the grain was divisible into four quarts.
For example, a gold alloy of fineness (that is, 99.2 per cent purity) could have been described as being 23-carat, 3-grain, 1-quart gold.

The carat system is increasingly being complemented or superseded by the millesimal fineness system in which the purity of precious metals is denoted by parts per thousand of pure metal in the alloy.

The most common carats used for gold in bullion, jewellery making and by goldsmiths are:

24 carat (millesimal fineness 999)
22 carat (millesimal fineness 916)
20 carat (millesimal fineness 833)
18 carat (millesimal fineness 750)
15 carat (millesimal fineness 625)
14 carat (millesimal fineness 585)
10 carat (millesimal fineness 417)
9 carat (millesimal fineness 375)

Weight of gold is usually denoted in sovereigns, grams and ounce or even kilogramme.