- Cabochon
- A smooth, domed cut without facets.
- Carat
- A unit of weight for gemstones (1 carat = 0.2 g); for gold, carat denotes purity.
- Carat (Gold)
- A measure of gold content; 24 carat equals pure gold.
- Casting
- Making jewellery by pouring molten metal into a mould.
- Chain
- Neck jewellery made of connected links.
- Chasing
- Decorating metal surfaces by punching and embossing.
- Citrine
- A yellow to golden-brown quartz.
- Coin
- A minted gold or silver piece, also used as an investment.
- Collier
- An elaborately crafted necklace, often set with stones.
- Copper
- An alloy metal that gives gold a reddish tone.
- Cubic Zirconia
- A synthetic, diamond-like gemstone.
- Cufflinks
- Jewellery for fastening shirt cuffs.
- Cultured Pearl
- A pearl cultivated on pearl farms.
- Cut
- The shape and finishing of a gemstone.