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Royal Coster
Diamonds Size
MM / INCH (Circumference)
48 / 1.89 48 4½ 8
49 / 1.93 49 9
50 / 1.97 50 K 10
51 / 2.01 51 L 11
52 / 2.05 52 6 12
53 / 2.09 53 13
54 / 2.13 54 14
55 / 2.17 55 O 15
56 / 2.20 56 P 16
57 / 2.24 57 8 17
58 / 2.28 58 18
59 / 2.31 59 R 19
60 / 2.36 60 9 S 20

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What is the most valuable precious metal? - Royal Coster Diamonds

What is the most valuable precious metal?

Precious metals

Metals that keep their quality are called precious metals. Despite external factors, these metals keep their quality, clarity and value. They are is resistant to corrosion and oxidation. Because these metals don’t look bad after a while, they are perfect for jewelry. The best known precious metals are:
  • Gold
  • Platinum
  • Silver
  • Palladium
  • Rhodium
  • Osmium
  • Iridium
  • Ruthenium
  • Tungsten
The precious metals gold and platinum will never go bad on their own because they are not affected by oxygen and moist. Silver is also sometimes seen as a precious metal, although silver can turn black after a while. Copper is even less precious, it can turn green after a while. The Statue of Liberty in New York is also made of copper. Gold, platinum and silver are the best known and most commonly used for jewelry, because they keep their quality well and are mostly resistant to corrosion. Below we explain the characteristics and differences per precious metal.


Gold can be found in the ground in various places in the world, but it is not always easy to be mined. It can be found in mines, but also in rivers. This affects the price, along with other factors such as the weight in carat, the color of the gold, as well as the gold price.


The 'gold karat' stands for the amount of fine gold that has been incorporated into a piece of jewelry. The amount of the carat, therefore, indicates how much pure gold a piece of jewelry contains. If you buy 8 and 9 karat gold jewelry in the Netherlands, it is said the jewelry doesn’t contain enough gold. This is done because the jewelry contains less than 50% gold. All gold under 14 karat does not count as ‘real gold’ in the Netherlands. 8 karat gold contains 33.3% gold and is also called 333 gold. 9 karat gold contains 37.5% gold and is called 375 gold. Other karats that are used a lot are 14, 18, 20, 22 and 24 karat gold. The higher the karat the more gold the jewelry contains. One karat is 1/24th of pure gold. One karat is 1/24th of pure gold. A lower karat also means a lower price.

14 karat gold contains 58.5% pure gold, this gold is also called 585 gold. In the Netherlands, 14 karat gold is widely used because it meets the standards that most jewelers impose. This amount is hard and could last a lifetime. In the Netherlands 18 karat gold is known as the more luxurious gold. This contains 75% gold and 15% other materials. 18 karat gold is also called 750 gold. At Royal Coster Diamonds we mostly use 18 karat gold for our jewelry, like this necklace:

20 karat gold is known as 833 gold and contains 83.3% gold. 22 karat gold is 916 gold and contains 91.6% gold. 24 karat is pure gold and contains at least 99.99% gold and is therefore called 999 gold. This is also the most expensive gold and is widely used in Arab countries and India.

Gold plated

If you want to buy gold jewelry on a lower budget, you can buy gold plated jewelry. The price of this is lower because only the outer layer of the jewelry is gold. This is usually plated with 14 or 18 karat gold. Gold plated jewelry often contains only 0.05% gold and damage faster to the point that it wears off. If this layer of gold is on a sterling silver piece of jewelry, it is called gold vermeil. Another option is gold filled jewelry. Here there is also a layer of gold around the base metal, but the layer here is thicker. With gold filled, the percentage of gold is at least 5% of the weight, so this is 100x as much as with gold plated. The way of making the jewelry is also different, with gold filled gold being applied to the base metal with pressure and heating.


Pure gold is yellow and fairly soft from itself. To make it stronger it is alloyed with other metals. To get another color of gold you can also mix the gold with different materials:
  • White gold consists of copper, palladium, silver, nickel, zinc and gold.
  • Yellow gold consists of silver, zinc, nickel and gold.
  • Rose gold consists of silver, copper and gold.
White gold is the most expensive color of gold. We also sell all these colors! View our assortment here.


Platinum is generally the most durable precious metal and therefore the most expensive. The price of platinum is higher because it is rarer, stronger and longer lasting than gold. To obtain a few grams of platinum, at least 10,000 kilos of platinum must be excavated and processed. About half of this remaining platinum goes to the industrial sector. Platinum looks a bit similar to white gold, but it's sturdier and less likely to be damaged. Platinum is heavier than gold and the color will never discolor or fade. In addition, platinum is hypoallergenic, so anyone can wear it. Because platinum is harder than gold, it is not necessary to mix it much with other materials, so only platinum 900 and 950 are used in the Netherlands. This means that it consists of 90% or 95% platinum and 10% or 5% other material. Platinum in jewelry is usually mixed with indium, palladium, ruthenium, rhodium or osmium.


Silver is not a very pure precious metal. It's popular because it's a cheap metal that lasts for quite some time. The purest form of silver is 999 silver, also known as fine silver. This is called 999 silver because it is 99.9% silver. In principle, the aim is 100% silver, but because it cannot be guaranteed due to small impurities, that’s why the term 999 is used. If silver is used for jewelry, this is usually not fine silver because, just like gold, it is often too soft, so silver is often mixed with other metals. The types of silver that are often used for jewelry are first and second grade silver. First grade silver or 925 silver, consists of 92.5% silver and 7.5% of another metal, often this other metal is copper. First grade silver is also called sterling silver. Second grade silver or 835 silver consists of 83.5% silver and the other 16.5% of another metal. All types of silver with less than 80% do not count as silver in the Netherlands. There are other types of silver, but the term silver should not be used if it is mixed with a metal that is not noble, or if it does not contain enough silver for Dutch standards. Of all the precious metals, Platinum is most expensive. Followed by 24 karat gold, but this is very fragile. 18 karat gold is a good, luxurious option if you want gold jewelry. At Coster, most of our jewelry is made of 18 carat gold.

If you are interested in this, view our assortment in the online shop or make an appointment to visit us. If you have any questions, you can always contact our diamond consultants.

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