750 gold indicates that the piece of jewelry or object is made of 18-karat gold, meaning it is 75% pure gold.
Understanding 750 Gold
When you see a hallmark that says "750" on a piece of gold jewelry or item, it's a quality stamp indicating the proportion of pure gold in the metal. Pure gold is 24 karat, and since 750 represents 75% purity, we can conclude the item is 18-karat gold.
Karat and Gold Purity
- 24-Karat Gold: This is considered pure gold, though in reality, it can be 99.9% pure. It's very soft and easily damaged.
- 18-Karat Gold: Represented by the "750" stamp, 18-karat gold contains 75% pure gold and 25% other metals (often alloys like silver, copper, or zinc) for added strength and durability.
Calculation of Gold Percentage
The percentage of gold in an alloy can be calculated as follows:
- Divide the karat number by 24. For 18-karat gold, the calculation is 18 / 24 = 0.75, which translates to 75%.
Why Use Alloys?
Pure gold (24 karat) is very soft, so alloying it with other metals creates items that are durable enough for everyday wear while still retaining a substantial amount of precious metal content. The 25% non-gold alloy can also slightly affect the color of the gold, for example, using more copper can make the gold more rose in color.
Key takeaways:
- A hallmark of 750 means that the gold item is 18-karat gold.
- 18-karat gold is 75% pure gold.
- The remaining 25% consists of other metals that add strength and sometimes color.
