June’s birthstones are Alexandrites and Pearls. We will be discussing each gemstone individually in this article, giving some history on both of these remarkable gemstones.
Alexandrite is often called “Emerald by day, Ruby by night”. Its name comes from the fact that the gemstone was first discovered in the emerald mines near the Tokovaya River in Russia’s Ural Mountains in 1830. Alexandrite is well known for displaying one of the most remarkable colour changes in the gem world — green in sunlight and red in incandescent light. However, the Alexandrite gemstone is so rare and so expensive that very few people have seen its natural beauty.
Legend has it that miners were working alone in the mountains one day, collecting emeralds when one miner gathered some stones, which looked like emeralds and took them back to camp at the end of the day. In the light of the campfire, the stones shone a brilliant shade of red which had the miners perplexed. When morning came and they saw that the stones were green again in the light, they realized that they had found a new and mysterious gem.
Pearls were given to Chinese royalty, while in ancient Rome, pearl jewellery was considered the ultimate status symbol. The abundance of natural oyster beds in the Persian Gulf meant that pearls also carried great importance in Arab cultures, where legend stated that pearls were formed from dewdrops that were swallowed by oysters when they fell into the sea. Before the advent of cultured pearls, the Persian Gulf was at the centre of the pearl trade and it was a source of wealth in the region long before the discovery of oil.
Alexandrite is a form of chrysoberyl that displays a colour change under varying lighting. Fluorescence is another property that differentiates the two gems. Chrysoberyl owes its yellowish colour to iron and usually shows no fluorescence. The red fluorescence of alexandrite can be observed using the crossed filter method.
Alexandrite would become one of the most prized gemstones amongst Russian Aristocracy. However, the abundance of alexandrite’s in Russia did not last forever. Practically all of Russia’s alexandrite was mined during the 19th Century. However, just when the gems were thought to be headed to extinction, even larger deposits were found in Sri Lanka and later on, Brazil became another contributor to the world supply of these gemstones.
In this post we will be discussing the Alexandrite’s quality factors such as colour, clarity, cut and carat weight.
Fine alexandrite is green to bluish-green in daylight and red to purplish-red in incandescent light. Its colour saturation is moderately strong to strong. Stones that are too light do not reach the quality of colour intensity seen in fine-quality gems. Stones that are too dark lack brightness and appear almost black. Sri Lankan alexandrites are generally larger than their Russian counterparts, but their colours tend to be less desirable. The greens tend to be yellowish compared to the blue-green of the Russian stones, and the reds of Sri Lankan alexandrite are typically brownish-red rather than purplish red.
ClarityAlexandrite tends to contain a few inclusions. There’s a dramatic rise in value for clean material with good colour change and strong colours. When certain types of long, thin inclusions are oriented parallel to each other, they can create an additional phenomenon called chatoyancy, or the cat’s-eye effect, increasing the alexandrite’s value.
Alexandrites are most commonly fashioned into what are called mixed cuts, which have brilliant-cut crowns and step-cut pavilions. Brilliant cuts have kite-shaped and triangular facets, while step cuts have concentric rows of parallel facets. Alexandrite’s pleochroism makes it a challenge for cutters. When fashioning alexandrite, cutters orient the gem to show the strongest colour change through the crown. It’s crucial to position the rough so the fashioned stone shows both purplish-red and green pleochroic colours face-up.
Most fashioned alexandrites are small, weighing less than one carat. Larger sizes and better qualities rise in price dramatically.
From a historical standpoint it is evident that Russian alexandrites are by far the most sought after gemstones since its discovery, however, Brazilian alexandrites may be better according to the Alexandrite tsar stone collectors guide. With better clarity and a strong colour change from rich blue-green to strong purple-red, the beautiful colour change of the Brazilian alexandrites is highly prized and the stones are always in strong demand. With so few Russian alexandrites available anywhere, their quality is nearly impossible to compare with alexandrites from later discoveries. Some fine alexandrites have been found at every important alexandrite deposit and the qualities of the best stones, as evidenced by the high prices they have fetched must surely rival even the very best Russian stones.
The cat's-eye effect is caused by the reflection of light off of minute, parallel, needle-like rutile crystals or hollow tubes within the stone. Cat's eye inclusions are aligned parallel to the crystallographic axis and the stones are always cut as cabochons with the fibrous need-like inclusions running across the narrow part of the stone as this is the best way to display the eye. The most valuable type of cat's eyes is the alexandrite cat's eyes where the stone displays both a cat's eye and a strong colour change. Other kinds of stones like tourmaline, quartz (tiger eye), sillimanite, scapolite, apatite and beryl may also display chatoyancy but these stones are referred to as tourmaline cat's eyes or quartz cat's eyes etc., and only chrysoberyl is referred to as "cat's eye" with no other designation.
Natural pearls, are pearls formed by chance. Cultured pearls have been given a helping hand by man. Today, nearly all pearls are cultured. By inserting a foreign object into a mollusc, pearl farmers can induce the creation of a pearl. From there, the same process of natural pearl creation takes place. The difference is that in this case, the inducement is intentional.
Natural pearls are the only gemstones grown inside of a living organism. Pearls are formed within oysters or molluscs when a foreign substance (most often a parasite - not a grain of sand) invades the shell of the mollusc and enters the soft mantle tissue. In response to the irritation, the mantle's epithelial cells form a sac (known as a pearl sac) which secretes a crystalline substance called nacre, the same substance which makes up the interior of a mollusc’s shell, which builds up in layers around the irritant, forming a pearl.
Natural pearls are extremely rare. Because the layers of nacre tend to maintain the irregular shape of the original irritant, natural pearls which are round or spherical are even rarer. Most natural pearls are irregularly shaped. In a completely natural state, only a very small percentage of molluscs will ever produce a pearl and only a few of them will develop a desirable size, shape, and colour; only a small fraction of those will be harvested by humans. It is commonly assumed that one in ten thousand molluscs naturally produce gem-quality pearls.
Cultured Pearls Defined
Simply put a cultured pearl is any pearl grown with the influence of human intervention. In the early part of the 20th century, Japanese researchers discovered a method of producing pearls artificially. Essentially, the method involves inserting a foreign substance, or nucleus, into the tissue of the oyster or mollusc, then returning it to the sea, allowing a cultured pearl to develop naturally. This practice was already quite widespread culturing hemispherical pearls known as mabe pearls. Kokichi Mikimoto is credited with perfecting the technique for artificially stimulating the development of round pearls in Akoya molluscs, receiving a patent for this technique in 1916. Although patented in 1916 this technique has since been improved upon and used extensively throughout the pearling world - no longer simply used to cultured Akoya pearls, but freshwater, South Sea and Tahitian pearls as well.
Mikimoto opened the door to a greatly expanded pearl industry in which pearls could be farmed like an agricultural crop. These cultured pearls could now be produced in sufficient quantities to make them available to virtually anyone. The cultured pearl industry has now far surpassed that of the natural pearl industry. Although a market still exists for pearls gifted to us by nature, these pearls are becoming more and more difficult to find, with rare full strands being auctioned for hundreds of thousands of dollars. Today, purchasing pearls from nearly any store in the world means purchasing a strand of cultured pearls.
Humans have been drawn to unusual and shiny objects since the birth of civilization. Why? Well because they are aesthetically pleasing, rich in history and represents a status symbol. And each of these birthstones has its own unique characteristics that we find very interesting. From pearls forming naturally overtime to the alexandrite having the ability to change colour in different light conditions. They are rare and hard to find, making owning them very special.
That’s why they are an industry leader in bespoke jewellery. Our team of experts are passionate about turning your vision into reality. We are meticulous and work with a high level of care and attention to detail. For more information on Alexandrite or Pearl gemstone, please feel free to get in touch with us at ICKINGER as we are more than happy to help.
At ICKINGER our team of experts will turn your vision into reality, creating a specially designed bespoke piece of jewellery just for you. We are meticulous and work with a high level of care and attention to detail. For more information on Alexandrite or Pearl gemstones, please feel free to get in touch with us at ICKINGER as we are more than happy to help.