French 22K gold-mounted bloodstone verge watch Circa 1750

Gold-mounted bloodstone and diamond-set verge watch
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A very fine and rare French 22 carat gold-mounted bloodstone and diamond-set verge Louis XV pocket watch, circa 1750. Hinged, frosted gilt full plate movement with square baluster pillars, Ø 30 mm, fusee and chain, a verge escapement, three-arm balance with flat balance spring, double-footed foliate and engraved balance cock, diamond endstone, silver regulation dial. White enamel dial with painted black Roman hours, outer minute divisions with black Arabic five-minute numerals, a winding aperture between 3 and 4 o’clock, blued steel beetle & poker hands. The case back is carved from a single piece of bloodstone mounted in gold, the bezel is decorated to match, a diamond-set thumb piece. Movement signed and numbered.
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Diameter: 40 mm
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Signed: Rentlràg à Paris
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Bloodstone is a beautiful, mostly, dark green stone that features red or brown spots that form as a result of impurities in the iron oxide. These spots look like blood splatters, giving the stone its English name. The stone is also referred to as a heliotrope, and gets this name from the Greek words helio, meaning ‘sun’, and tropos, meaning ‘toward the sun’. It’s said that the colour is also reminiscent of heliotrope plants that face towards the sun. The solid green colour that encompasses the rest of the stone is brought in as a result of the amphibole or Chlorite minerals found in the green Chalcedony. Chalcedony is a cryptocrystalline form of silica that’s composed of fine intergrowths of moganite and quartz, the minerals that make up most agate stones too. Because of its varied composition, the green in bloodstone is not always evenly distributed and may have blue or yellow streaks in addition to green. It has been a popular gemstone for at least two thousand years.