| 摘要 |
FIELD: stone working practice; coloration of natural jewelry gems and stones. SUBSTANCE: natural agates are colored in two stages. The first one resides in treating agates by alkali solutions (LiOH, NaOH, KOH) for 5-25 h under hydrothermal conditions at 50-300 C and under pressure 50-500 atm. In the second stage, COLORING agents are used such as, potassium bichromate, nickel oxalate, potassium manganate, etc. Treatment is conducted under hydrothermal conditions at 50-300 C and pressure 50-500 atm for 5-48 h depending on coloration intensity. EFFECT: increased coloration intensity and contrast range.
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