Transparent rhodonite is considered one of the most difficult of all gems to facet because of its perfect cleavage and brittle, uneven fracture. This article describes a technique for successfully faceting gem rhodonite that was developed through experiments on eight crystals from the North mine at Broken Hill, New South Wales. This was accomplished through a systematic structural, crystallographic, and optical analysis and the use of a nonconventional faceting approach—the “greasy lap” technique. This method uses a mixture of petroleum jelly and diamond grit to charge a non-embedded lap, allowing the diamond grit to “roll free” during the lapping process.
Transparent rhodonite is considered one of the most difficult of all gems to facet because of its perfect cleavage and brittle, uneven fracture. This article describes a technique for successfully faceting gem rhodonite that was developed through experiments on eight crystals from the North mine at Broken Hill, New South Wales. This was accomplished through a systematic structural, crystallographic, and optical analysis and the use of a nonconventional faceting approach—the “greasy lap” technique. This method uses a mixture of petroleum jelly and diamond grit to charge a non-embedded lap, allowing the diamond grit to “roll free” during the lapping process.
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