When you walk into a jewelry store, you will usually find many types of gold on offer — yellow gold, white gold, rose gold, and even platinum. But after wearing a beautiful piece of gold jewelry for some time, it suddenly starts to look dull. Could the seller be deceiving you? Having the right knowledge will help you receive quality gold jewelry and avoid being misled.

In jewelry making, rhodium (Rd) is used to plate white gold rings in order to achieve a pure white color. This is the standard process for plating 14K and 18K white gold jewelry. Over time, the rhodium coating reacts with oxidation and perspiration, causing the jewelry to gradually dull and darken. The rate at which this occurs depends on the quality of the plating and the acidity of the wearer's sweat.

Calette Diamonds gold, however, relies on a gold alloy formulated with palladium (Pd) for the jewelry setting, which better preserves the color of the gold. We also use 75% gold — or 18K — in the production of all our jewelry settings, which provides and a stronger grip for diamonds and gemstones.

To understand a little more about gold: the core ingredient in all of these jewelry types is gold itself — a metallic element, number 79 on the periodic table, with the symbol ‘Au'. It has a characteristic lustrous yellow appearance and is extremely malleable, giving it very low strength and hardness. It rarely reacts chemically with other substances, making it an inert metal. Historically regarded as a rare and precious material, it exists at roughly six parts per billion in the Earth's crust. It is used in jewelry, medical instruments, various industries, and as an international monetary reserve.

However, because gold is naturally so soft, it cannot be used on its own in jewelry production. Other metals must be mixed in to increase its strength — which gives rise to the term Karat (K), used to classify the purity of different types of gold.

Types of gold classified by purity. Credit: Shopify

Karat comes from the word ‘Karat' — the unit used to measure the proportion of gold purity in the United States and other countries. The higher the number before the K, the lower the proportion of other metals mixed in. The other metals used in the alloy include silver (Ag), palladium (Pd), magnesium (Mg), and can also sometimes contain nickel (Ni). However nickel causes allergic reaction in some people, therefore we recommend using jewelry without nickel. At Calette Diamonds, we only use Nickel Safe Jewelry in accordance with the EU Nickel Directive.

For more details please see this article: Nickel Allergy in Jewelry: What are the symptoms?

When expressed as a percentage of purity, gold can be classified as shown in the table below:

You can easily identify the gold content of a piece by looking at the inside of the jewelry, where a three-digit number is stamped, as shown in the image. However to be certain, you should ask your jeweler for a gold testing report to ensure that contents of the gold and its alloy. See a sample of the gold report below.

The number 750 stamped on a ring indicates that the piece is made from 75% gold,
or 18K

Gold bars and traditional Thai gold jewelry sold at gold shops are typically 96.5% pure — meaning 96.5% gold content, with the remainder being other metals mixed in to help the gold hold its shape.

Beyond the types of gold used in trading or jewelry, there are other gold-related terms worth knowing:

White Gold vs Platinum

In Thai, we tend to call White Gold "ทองขาว" (white gold) and Platinum "ทองคำขาว" (white gold) — the names sound remarkably similar. But when referred to in English as White Gold and Platinum, it becomes immediately clear that they are two entirely different metals.

White Gold is gold alloyed with at least 10% palladium (Pd) or nickel (Ni) to give it a bright, white appearance. It is strong and durable, making it well-suited for producing jewelry set with diamonds and gemstones. For those who want gold in other colors, Rose Gold — also known as Pink Gold — is 18K gold alloyed with a higher-than-usual proportion of copper (Cu) and zinc (Zn), resulting in a warm, rosy tone.

*A platinum ring will have Pt950 stamped on the inside of the band*

Platinum is an entirely different metal — silver-gray in color, similar in appearance to white gold — with the symbol Pt, sitting at number 80 on the periodic table, just after gold (Au). Like gold, platinum is used in jewelry for its strength and durability, and it can be crafted into beautiful, intricate designs. Platinum is also used in engineering and in the manufacture of medical instruments.

If you are interested in designing a ring in a style that is uniquely yours, feel free to discuss your ideas with our team at Email: info@calettediamonds.com or Line: @CaletteDiamonds

Clearing the Confusion: Why Does Gold Jewelry Change Color?

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