Sloane MS. occurs another recipe for the same purpose.

Ahab's "ivory house which he made" must have been either covered
with a very thin veneer, or else the ivory was used as inlay, which
was often the case, in connection with ebony. Ezekiel alludes to
this combination. Ivory and gold were used by the Greeks in their
famous Chryselephantine statues, in which cases thin plates of
ivory formed the face, hands, and exposed parts, the rest being
overlaid with gold, This art originated with the brothers Dipœnus
and Scillis, about 570 B. C., in Crete.

"In sculpturing ivory," says Theophilus, "first form a tablet of
the magnitude you may wish, and superposing chalk, portray with
a lead the figures according to your pleasure, and with a pointed
instrument mark the lines that they may appear: then carve the
grounds as deeply as you wish with different instruments, and sculp
the figures or other things you please, according to your invention
and skill." He tells how to make a knife handle with open work
carvings, through which a gold ground is visible: and extremely
handsome would such a knife be when completed, according to Theophilus'
directions. He also tells how to redden ivory. "There is likewise
an herb called 'rubrica,' the root of which is long, slender, and
of a red colour; this being dug up is dried in the sun and is pounded
in a mortar with the pestle, and so being scraped into a pot, and a
lye poured over it, is then cooked. In this, when it has well boiled,
the bone of the elephant or fish or stag, being placed, is made red."
Mediæval chessmen were made in ivory: very likely the need for a red
stain was felt chiefly for such pieces.

The celebrated Consular Diptychs date from the fourth century onwards.