Modelled as a princess frog holding a button-shaped clam pearl weighing 106.85 carats (27.33 - 27.41 x 19.25mm), the frog set with circular-cut tsavorite garnets together weighing approximately 9.50 carats, highlighted by cabochon red hardstone-set eyes together weighing approximately 1.45 carats, decorated with brilliant-cut diamond-set leaves, to the detachable crown highlighted by brilliant-cut diamonds, the diamonds together weighing approximately 1.20 carats, mounted in 18 karat white, yellow and blackened gold.
Accompanied by a Tridacna clam shell measuring approximately 12 x 15 x 20cm.
Accompanied by GIA report numbered 2276719465, dated 3 January 2018, stating that the 106.85 carat pearl is natural saltwater, tridunacna species, White colour, with no indications of treatment.
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THE GIANT CLAM
Tridacna, or known as the giant clam, is a genus of large saltwater clams. They have heavy shells, fluted with 4 to 6 folds. Tridacna clams can produce large white pearls with an undulating, porcelain-like surface, which may be described as “non-nacreous pearls”. The “Pearl of Lao Tzu”, is the world’s largest pearl weighing 6.4 kilograms; it was said to have been found inside a Tridacna gigas by a Filipino diver in 1934.
Pearls develop organically in water-living mollusks, such as clams, mussels and oysters. The pearl formation due to external irritant is basically the same in all mollusks. Most pearls come from oysters. It’s unusual for clams and mussels to produce pearls, but it is possible. According to studies, only one in 5,000 clams forms a pearl. When they do, the pearl is quite valuable.
For clam pearls, there are no nacreous layers. The prismatic layers of clam pearls are made up of calcite fibres and conchiolin which are radially arranged around the inner core, so that light striking and penetrating the surface interacts with the fibres producing the optical phenomenon known as “Flame”. The larger the pearl, the lesser flame appearance and not all clam pearls display flame.
Clam-produced pearls of the perfect colour and shape are quite valuable. They are considered treasured gems because they are so uncommon. Nowadays, machines shuck most clams, which makes it nearly impossible to uncover a pearl. In addition, most clam produced pearls are so misshapen that they are not desirable for jewellery. They come in many shapes, with perfectly round and free of blemishes ones are comparatively rare to collect.