24K Gold (999)
Near-pure gold (99.5–99.9% gold). Too soft for daily-wear jewelry. Sold as coins, bars, and biscuits for investment.
24K refers to gold at 24 karats, meaning 100% pure. In practice, 'pure' gold is sold at 995 (99.5%) or 999 (99.9%) purity. It is too soft for settings and scratches with any friction. Preferred for investment because it carries almost no making charge (0.5–3%) and retains nearly all resale value.