22K gold jewelry means that 22 part of the piece are gold and 2 parts are another metal. In other words, 91.67% is pure gold while the other 8.33% is composed of metals like silver, zinc, nickel and other alloys. These other metals make the gold harder and more durable for jewelry making.
22K gold isn’t a “solid” choice for diamonds and heavily studded jewelry but are a smart choice for plain gold jewelry, like the wedding bands pictured above.
Why not choose 24K gold if possible?
It’s simply too soft for jewelry making needs. Even gold bullions aren’t pure gold. Yes, they contain their full stated weight in gold but have an additional weight in alloy to harden and protect them against wear.