Nacre, which is also called as mother-of-pearl, is crystalline substance which creates iridescent visual effect accredited to pearls. The nacre is certain organic substance that is secreted by molluscs over intruding irritant.
It is quite resilient and strong material which is transparent and lightweight, allows light passing through its surface, and create subtle glow on pearl’s surface. By clicking here in this post, you will get few more details about pearl nacre.
Composition of nacre
Composition of nacre is primarily with crystallized calcium carbonate and conchiolin. The conchiolin is dark-coloured substance which is secreted by mollusc during initial phases when pearl formation takes place.
Conchiolin is a kind of organic protein which acts like a glue or adhesive. Usually, it will be the initial layer deposited by the pearl sac.
Composed with aragonite platelets
Nacre contains many aragonite platelets and elastic biopolymers e.g. lustring and chitin and also silk-like proteins. These aragonite platelets can only be seen by using a 2000x electron microscope.
They are polygonal and hexagonal in shape, and average size is between 0.35 to 0.5 microns thick and across about 3.0 to 6.0 microns. It will be considered soft gem when it is combined with organic biopolymers, the protein the mollusc secretes naturally.
Mollusc will secrete nacre and pearl is formed
Mollusc secretes continuously concentric nacre layers around the nucleus in irregular manner and microns-thin crystalline sheets are laid down that may not be perfectly together, and as a result, irregular layer like mountains and valleys get formed.
Such patterns are referred as own fingerprint of pearl as each layer is unique in composition.
Nacre will be actual pearl’s beauty
Size and shape of these aragonite platelets will ultimately influence a pearl’s 2 most important qualities are lustre and orient. The thinness and transparency of platelets is almost like wavelength of a white light, and hence light rays’ transmission and refraction will be possible all throughout its crystalline layers.
After coming in contact with the pearl surface, a significant amount of white light will be able to penetrate top layer and also will work its way via the strata of the nacre.
Each platelet where the light will come in contact, will act as tiny prism that will break up the beam, refract back subtle rainbow of colour which is visible on pearls’ surface.