man has used gemstones
since ancient times genuine gemstones come from nature
minerals rocks or even
certain organic
materials shaped cut and
polished to bring out their colors and brilliance
the rarest ones are classified as precious gems the others as
semi-precious this
semi-precious stone is called Blue John it's a rare variety
of the mineral fluorite
also known as fluorspar while common fluorspar is
cream or white blue John
also has magnificent bands of purple blue and
yellow there's only one
place in the world where Blue John is found and
that's in the village of
Casselton
Derbyshire in central
England the stone comes from a cavern located
some 50 meters deep in a
hillside the miners don't use explosives because the
stone is quite soft and
brittle in its
natural state and blasting
would simply
shatter it instead they use
drills to carefully dislodge pieces of Blue John
from the rock wall you
they carry the Blue John to
the surface to the minds workshop where stone
processors manually wash
off the clay
the stone is wet due to
having been underground for some 240 million years
so they put it into an oven at low heat
80 degrees Celsius when the
stone comes
out of the oven a couple of
weeks later all of its moisture has evaporated
the dried stone however is
still brittle
so they submerge it in a
bowl of liquid resin then place the bowl into a vacuum
oven at 80 degrees Celsius
this process
draws out all the air and
forces the resin deep into the stones pores the
stone then goes into
another oven at 50
degrees Celsius for about
12 hours this hardens the resin stabilizing the
stone so that it can be
worked without
crumbling to create large
items such as goblets and bowls the workshops artisans
turn the stone on a lathe
to avoid fracturing it they must work the Blue
John slowly and with
diamond tip tools diamond being harder than all other
rocks cuts with less force
and stress to supply jewelry makers the mine workshop
saws stones into slices
using a diamond edge saw at the jewelry workshop a
gemologist examines the
slices on a lightbox to highlight the coloring and
any flaws this helps determine which
parts of the slice will
yield the most striking gemstones meanwhile in another part of the
workshop a silversmith
crafts a piece of
jewelry in this case a
sterling silver ring which will receive a Blue John
gemstone she bends then
Sauter's
together the ends of the
Rings shank the part that encircles the finger after
grinding the solder seam
flat she fuses
the top of the ring called
the setting onto the shank then she polishes the
ring and passes it on to
the gemologist
who takes a slice of Blue
John and with a diamond edged lapidary saw cuts out
the gemstone shape making
it slightly larger than the setting next she glues
on a backing cut from mother-of-pearl
just like the white light on which the
gemologist examined the
Blue John slices this mother-of-pearl backing highlights
the colors in the stone
now using a diamond grit
grinding wheel she shapes the stone to fit perfectly in
the setting she applies
glue to the setting and fits
the gemstone snugly inside once
the glue dries she uses a diamond
grit sanding belt to smooth
down the edges gradually transforming the rough
oval into a sleek dome this
gem shape is known as a cabochon
finally she polishes the
entire ring surface until the silver and the richly
hued Blue John glisten
whether it's one or several the shape funky or traditional a gemstone sure
makes a piece of jewelry Rock
