Fine Jewelry Metals - 18K, PT950 & S925

Jul 21, 2021
3 min read

Updated: Feb 11

Jewelry consists of two core elements: the gemstone and the metal. Once the gemstone is chosen, the metal significantly affects durability and long-term wear. Materials that lack stability may oxidize or discolor, while insufficient strength can compromise the security of the setting.

18K gold, platinum, and sterling silver are the most common jewelry metals, each with distinct properties. Understanding their differences supports a well-informed selection.

18K Gold (AU750)

18K gold consists of 75% pure gold, with its composition divided into 24 parts, 18 of which are gold—hence the hallmark AU750. Other common alloys include 14K (58.5% / AU585) and 9K (37.5% / AU375); lower gold content generally means reduced stability and oxidation resistance.

18K gold is available in white, rose, and yellow tones. Each contains 75% pure gold blended with 25% alloy metals to achieve its color while enhancing overall strength.

18K gold (AU750) is widely used for setting diamonds and precious gemstones, valued for few primary reasons:

1. High Hardness

18K gold offers strong structural integrity, providing secure support for gemstones and good resistance to scratches and daily wear.

2. Oxidation Resistance

It maintains its luster well under normal wear and demonstrates reliable resistance to oxidation over time.

3. Market Liquidity

18K gold jewelry is widely tradable and recyclable, allowing value recovery in line with prevailing gold prices.

Consideration: Periodic Refinishing

Depending on usage, refinishing every few years is recommended to maintain optimal appearance.

Platinum (PT950)

PT950 contains 95% platinum alloyed with 5% other metals, and is a standard for high-purity platinum jewelry.

Naturally silvery-white and color-stable, platinum resists oxidation and maintains its appearance over time. Its high density and structural stability make it suitable for long-term wear and precise stone setting.

Platinum (PT950) Key Strengths and Considerations:

Strength 1: Non-Oxidizing

Platinum does not oxidize, allowing it to maintain its natural luster over time.

Strength 2: Substantial Weight

With a very high density, platinum has a noticeable weight, making platinum jewelry significantly heavier than 18K gold or sterling silver.

Strength 3: Market Liquidity

Platinum jewelry is widely recyclable. If platinum prices rise, reselling old pieces may offer an opportunity to recover value.

Consideration 1: Moderate Hardness

Platinum provides sufficient strength to secure gemstones, though its resistance to surface scratches is moderate.

Consideration 2: Single Natural Color

Platinum is naturally available only in a silvery-white tone.

Sterling silver (S925)

Sterling silver (925) contains 92.5% silver alloyed with 7.5% other metals and is a widely used silvery-white jewelry material.

As silver is relatively soft and prone to oxidation, pieces are often rhodium-plated to improve surface stability. Regular maintenance is recommended to retain its shine.

Silver (S925) – Key Strengths and Considerations:

Strength 1: Affordable

Sterling silver jewelry is widely accessible in price.

Strength 2: Easy to Clean

Although it requires regular cleaning, maintenance is straightforward.

Consideration 1: Softness

Silver is relatively soft and prone to scratches or deformation, making it less suitable for secure stone settings.

Consideration 2: Oxidation

It oxidizes when exposed to air and may darken over time. Rhodium plating typically lasts 3–6 months, depending on wear.

Consideration 3: Limited Resale Value

Due to its low intrinsic value, sterling silver generally offers minimal resale significance.