STORIES - Precious Metal Purity: What Do 750 and 585 Actually Mean?
Look inside any gold ring and you'll usually find a small stamp: 750, or perhaps 585. These numbers say nothing about the design, yet they say everything about what the piece is actually made of. In this blog, we explain what precious metal purity means, how it's measured, and why it matters when choosing a piece of jewellery.
What is precious metal purity?
Pure gold, in its natural state, is very soft, too soft to hold its shape in a ring worn daily. That's why gold is mixed, or alloyed, with other metals such as silver, copper or palladium. This gives it strength, durability and, depending on the mix, its colour.
Precious metal purity indicates how much pure gold a piece actually contains. This can be expressed in two ways: karat(K) or a three-digit number, such as 750 or 585.
Karat vs. the three-digit number
Pure gold is 24 karat, or 100% gold. Every karat below that represents a fraction of pure gold in the alloy.
The three-digit number works the same way, but expressed per thousand parts:
- 24K = 999/1000 — pure gold, essentially never used in jewellery due to softness
- 18K = 750/1000 — 75% pure gold
- 14K = 585/1000 — 58.5% pure gold
- 9K = 375/1000 — 37.5% pure gold
So 750 and 18K describe the exact same purity, just written differently. The same goes for 585 and 14K.
750 vs. 585: what's the real difference?
750 (18K) contains more pure gold. This gives it a richer, warmer colour and a higher intrinsic value. It's also slightly softer than 14K, since there's less of the harder alloy metals mixed in.
585 (14K) contains less pure gold, making it more durable and scratch-resistant, a practical advantage for pieces worn daily, such as wedding bands. It's also more affordable, since a larger share of the metal is the alloy rather than gold itself.
Neither is objectively "better." It's a trade-off between purity, durability and price.
And white gold, rose gold?
The karat number tells you how much pure gold is present, not the colour. Colour comes from the other metals in the alloy:
- Yellow gold stays closest to gold's natural colour
- White gold is alloyed with metals like palladium or silver, and typically finished with a rhodium plating for its bright white shine
- Rose gold is alloyed with a higher proportion of copper, giving it its warm pink tone
An 18K white gold ring and an 18K rose gold ring contain exactly the same amount of pure gold (75%) just combined with different metals.
Why it matters when choosing jewellery
Precious metal purity affects more than just the stamp inside your ring:
- Value — a higher gold content means a higher intrinsic value
- Colour intensity — higher purity gold has a deeper, richer tone
- Durability — lower purity gold is generally harder and more resistant to daily wear
- Hypoallergenic properties — higher purity gold contains less of the alloy metals that can occasionally cause skin sensitivity
Understanding these numbers means you know exactly what you're wearing and can make a choice that fits both how the piece looks and how it will hold up over the years.