"Hi all, does anyone know what: En R?ille enamelling is? "
To quote from GIA’s “Jewelers’ Manual:” “en resille (ahn-ray-see).
A rare form of decoration, requiring great skill and craftsmanship.
It is a process in which a base of glass or rock crystal has incised
on it fine hairlike lines to form a design. The pattern is lined
with gold; the tiny cells thus formed are filled with soft, low-fire
opaque or translucent enamels. The resulting effect, after firing
and polishing, is not unlike that of a delicately woven net.”
Personal note: I’m not at all familiar with this process, but I know
a fair amount about gem materials, including rock crystal. The
application of heat to any rock or mineral is a risky process and
must be done with extreme care, raising the temperature in small
increments over a long period of time. Cool-down must also be very
slow, usually over a period of 12 or more hours in a closed oven.
Even then, cracks are possible if there are inclusions or other risk