The colouring of the aforesaid mass follows, in which it is made most like to Gemmes.
IT behooveth that colours be taken from metals and mine∣rals, namely from copper, iron, gold, silver, Wismuth, Mag∣nesia and Granate: of other colours I know nothing of cer∣tainty, copper commonly makes a colour green like the Sea, copper of iron grass-green; Granate smaragdine colour, iron yellow or Iacynth; Gold the best skie colour; Wismuth common skie colour; Magnesia Amethystine: mixt, they give other colours; E. gr. Gold mixt with Silver gives an Amethyst colour; Iron and Copper, a pale green; Wismuth and Mag∣nesia, a purple; Silver and Magnesia various colours like an Opal.
Images are also made of diverse colours, if the masses of diverse colours be broken into bits and mixt be put upon the type, &c. And if thou desirest an opac mass (green, red, skie colour, &c.) add a little calx of Tin darkning, on which as on a Basis the colours insist. For example; in making a Tur∣coise stone or a Lazulus, mingle to the Azuremade of the sil∣ver Marcasit or Zafora (to colour the mass) the calx of tin, that they may melt together, and before the impression be made, put upon the type some prepared gold, then spread and put upon this the aforesaid glass; and the fusion and impression being