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Aqua Regia Recipes For Testing Gold

Aqua Regia

Aqua regia or aqua regis (Latin for royal water or king's water) is a highly corrosive, fuming yellow or red solution, also called nitro-hydrochloric acid. The mixture is formed by freshly mixing concentrated nitric acid and concentrated hydrochloric acid, usually in a volumetric ratio of 1:3 respectively, although other ratios are made and used to test varying purities of gold. It was named so because it can dissolve the so-called "royal metals," or noble metals, gold and platinum.

Aqua Regia is one of only a few solvents that will dissolve gold.

One can also use aqua regia to test high karat gold to determine purity or fineness.

!! -- IMPORTANT -- !!
These acids are very corrosive and very dangerous!

They will burn your skin and ANY thing else they come in contact with!

The fumes are toxic and hazardous, they will burn skin too!

Mixtures containing both nitric and hydrochloric acids off-gas chlorine gas and may explode if their container is sealed. Never seal a container of aqua regia. Always leave the cap loose to let the gas escape!

These recipes of Aqua Regia will last approximately 3-4 weeks before they lose potency.

Aqua Regia Recipes
To Test For: Acids Ratio Chemical
Gold Plate Nitric, Water 3:1 HNO3
Silver Plate Nitric, Water 3:1 HNO3
500-999 Silver Nitric, Water 3:1 HNO3
8k-14k Karat Gold Nitric n/a HNO3
10k-18k Karat Gold Hydrochloric, Nitric, Water 1:50:12 respectively* 1HCl+50HNO3+12H2O
14k-22k Karat Gold Hydrochloric, Nitric 3:1 3HCl+1HNO3
18k-24k Karat Gold Hydrochloric, Nitric 4:1 4HCl+1HNO3
20k-24k Karat Gold, Platinum Hydrochloric, Nitric 41:9** 41HCl+9HNO3

* ALWAYS add acid to water! NEVER add water to acid!

** True Aqua Regia