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 gemstone 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. From where they carry the Blue John to the surface to the mines 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 and 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. Here you see 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 gemstone 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.