Trithemius - The Art of Drawing Spirits into Crystals
Procure of a lapidary good clear pellucid crystal, of the bigness of a small orange, i.e. about one inch and a half in diameter; let it be globular or round
each way alike; then, when you have got this crystal, fair and clear, without any clouds or specks, get a small plate of pure gold to encompass the crystal
round one half; let this be fitted on an ivory or ebony pedestal.