By Natalya BREDIS, head of the Department of Optico-Physical Research, National Restoration Research Center, Ukraine (Kiev)
In times of old, one of the most coveted gems in many parts of the ancient world, especially the Arab East, was known by the name of "lou-lou". Its name in Old Russian chronicles and legends was "zhenjchug" or "zhemchug"-a derivation from Chinese "chjenchzu". It was used in a whole range of ornaments. Strings of pearl beads adorned the garments of princes and gentry and also of the common folk. In that day and age embroidery with pearl beads was regarded in Russia as a purely feminine craft and whole workshops were set up in cities and towns in which teams of females of different ages worked long hours in well-lit "svetlitsy" chambers. Our museums possess a wealth of objects decorated with pearl beads. One of the questions facing art experts now, however, is this: Are all of these different pearls really what we think they are? This question is now on the agenda of what we call scientific attribution.
WHAT IS PEARL?
Speaking in strictly scientific terms, natural pearl is a calcareous concretion of globular or irregular form. A pearl is formed around a foreign body either against the inner side of a shell or within the mollusc, sealed off as a cyst. It consists of concentric films of nacre, consisting of aragonite, which also forms the smooth lustrous lining (mother-of-pearl) in the shells of pearl-bearing molluscs. This radial or concentric structure is the main distinction of a genuine pearl.
Its main components include aragonite, organic conchiolin, water and micro admixtures of aluminum, barium, iron, silicon, manganese, copper, and molybdenum the levels of which can vary both in quantities and quality. Aragonite present in the pearl shells and beads belongs to the class ofcarbonites Ca (?03) with its hardness factor, by the Mohs hardness scale, being 3.5 to 4.0. Its density is from 2.65 to 2.75 g/cm 3 . Its structure fits tha ... Read more