Inclusions of rutile (dark crystal and fine needles) and clusters of zircon grains in umbalite garnet, Tanzania
Inclusions of rutile (dark crystal and fine needles) and clusters of zircon grains in umbalite garnet, Tanzania
Inclusions of anatase crystal and rutile fibres in rock crystal from Brazil
Inclusions of anatase crystal and rutile fibres in rock crystal from Brazil
Fire opal, Mexico
Fire opal, Mexico
Two-phase inclusions in sapphire, Sri Lanka
Two-phase inclusions in sapphire, Sri Lanka
Agate from Anzi, Maroc
Agate from Anzi, Maroc
Two-Phase inclusions and rutile needles in rock crystal from Brazil
Two-Phase inclusions and rutile needles in rock crystal from Brazil
Fluid inclusions containing mica and quartz, in aquamarine from Pakistan
Fluid inclusions containing mica and quartz, in aquamarine from Pakistan
Epigenetic inclusion (probanly melanterite) in quartz, Brazil, crossed polarisers
Epigenetic inclusion (probanly melanterite) in quartz, Brazil, crossed polarisers
 
 

Pearls - The Jewels of the Seas

History and Cultivation

The first pearls were discovered in antiquity by chance by fishermen. As a precious jewel they have always fascinated man as symbols of love, joy and happiness.
Pearls come from oysters (salt water) or pearl mussels (freshwater) and differ in size, colour, shape and lustre. An injury or a tiny foreign body irritates the animal and causes the secretion of the conchiolin (mother-of-pearl or nacre) which isolates the foreign body in concentric circles.

Since men have discovered this secret of nature, they have started culturing pearls. Man can give the initial ignition, by placing an “irritant” in the animal, however what the shell then produces can not be significantly influenced. Man can therefore create a pearl but can not influence the colour nor the quality. Therefore large, perfectly round cultured pearls with high lustre and flawless surface quality are rare and their prices are correspondingly high. The cultivation of pearls is also very complex and time-intensive.

Firstly, it is necessary to cultivate the oyster itself and to obtain a sufficient quantity of bivalves. Then, the insertion of a piece of mantle tissue (from another bivalve), together with a round mother-of-pearl core is inserted, which is a delicate operation requiring great skill. The oyster is then immersed in water for several years depending on the variety. During their immersion, they should be cleaned and monitored regularly. The quality and temperature of the water have a great influence on the quality of the pearls.