Gemstones for Firing In Place

This table combines the various firing schedules for different types of metal clay with a list of gemstones that have been demonstrated to be suitable for firing in place. The firing temperature and time is shown at the top of each column.

For each type of gemstone, use the coloured grid to determine which firing schedule(s) to use.

If you are in doubt about whether a gemstone will survive firing, pre-fire it wrapped in fibre blanket.

Note that some gemstones, particularly green ones, may change colour during firing.

Gemstone

600șC 30 mins

650șC 20 mins

650șC 30 mins

700șC 10 mins

700șC 15 mins

780șC 10 mins

800șC 30 mins

850șC 20 mins

870șC 10 mins

900șC 10 mins

900șC 120 mins

999șC 120 mins

Alexandrite

Alexandrite, Cat's Eye

O

O

Andalucite

O

O

Apatite

O

O

Chrome Diopside

O

O

Chrysoberyl

O

O

O

O

O

Corundum

Cubic Zirconium

O

O

Dichroic glass

O

O

O

O

O

O

O

O

O

Epidote

O

O

Feldspar

O

O

O

O

O

O

O

O

O

Garnet, Almandine

O

O

Garnet, Champagne

O

O

Garnet, Colour change

O

O

Garnet, Demantoid

O

O

O

O

O

O

O

O

O

Garnet, Grossular

O

O

Garnet, Hessionite

O

O

Garnet, Pyrope

Garnet, Rhodolite

Garnet, Tsavorite

Goldstone, Blue

O

O

O

O

O

O

O

Haematite

O

O

O

O

O

O

O

O

O

Labradorite

O

O

O

O

O

O

O

O

O

Moldovite

O

O

O

O

O

O

O

O

O

Moonstone

O

O

Obsidian

O

O

O

O

O

O

O

O

O

Peridot

O

O

Ruby

Ruby, Cats eye

O

O

Ruby, Colour Change

Ruby, Star

O

O

Sapphire

Sapphire, Black Star

O

O

O

O

O

O

O

O

O

Sapphire, Cats eye

O

O

Sapphire, Colour change

Sapphire, Padparadscha

O

O

O

O

O

O

O

O

O

Sapphire, Star

O

O

Spectrolite

O

O

O

O

O

O

O

O

O

Spinel

O

O

Spinel. Blue

O

O

Spinel, Cats Eye

O

O

Spinel, Colour Change

O

O

Spinel, Star

O

O

Tanzanite

O

O

Tanzanite, Blue

O

O

Tanzanite, Green

O

O

Tanzanite, Red

O

O

Tanzanite, Violet Blue

O

O

Zircon

O

O

Zircon, Blue

Zircon, Honey

O

O

Zircon, Orange

O

O

Zircon, White