A Troy ounce, a bar of pure gold. One Troy ounce equals 31.10 grams. Many people regularly ask me to clarify exactly what the carat numbers that are stamped on the jewelry mean. So here is some information on the different karats of gold, in addition to some information on the different colors of gold. First, the carat is the unit of measurement used to determine the purity of gold. Be careful, the carat can also mean the unit weight of gemstones and pearls. Pure gold equals 24k, so the other karat numbers are the fractional figures of the proportion of pure gold and alloy that ends up in the gold recipe used. For example: When 18k is stamped on a jewel, it means that there are 18 parts pure gold out of 24 and 6 parts alloy in the gold in question, therefore the jewel is made of 75% pure gold. pure gold. Note that Europeans identify pure gold with 1000. Thereby : 24k=1000 22k=917 18k=750 14k=585 10k=417 Second, there are several colors of gold, but only yellow gold is found as a native metal in soils. This is why, depending on the color of gold that one wishes to obtain and manufacture, one modifies the recipe for the alloys added to the pure gold. The main composition of the alloy recipe for yellow gold is fine silver (pure silver) and some copper. In this way to design rose gold the alloy recipe becomes mainly copper and a little fine silver. To obtain white gold, pure gold is simply added as an alloy of nickel or palladium (the version of white gold with palladium is more expensive). Therefore, when you pay for the purchase of gold, you pay for the number of carats of gold that the jewel contains and not for the color of the gold. Except in the case of palladium white gold as mentioned above. However, nowadays, white gold has a rhodium finish, which is a light plating that makes the white gold shine whiter. This rhodium having become expensive adds an additional cost to the jewel, subsequently, white gold is sold for a little more than yellow gold or pink gold, always according to the carat. Hoping you have helped a little to decipher the whole thing. Do not hesitate to contact me if you have any questions. Thank you !