Muriatic acid, which is used to adjust the total alkalinity and PH in pools, is also an ingredient in "aqua regia" (a mixture of nitric and hydrochloric acid). Aqua regia is made of 1 part nitric acid and 3 parts muriatic acid. Aqua regia dissolves pure 24 karat gold.
Other stones, such as opals, turquoise and pearls can be damaged by pool chemicals. Should you happen to lose a diamond or small piece of jewellery in a pool, it can be very difficult to find. It is best not to wear jewellery in swimming pools and/or hot tubs.