Category Archives: Gemstones

Amber is interesting as a gemstone as it is originally from tree resin. It is not sufficent to classify hardened tree resin as amber, as in order to be amber polymerisation must first occur. This is the process of creating many chains of bonded atoms, called polymers, this process does not have to be fully understood but it is important to know that without sufficent polymerisation amber is soluable in solvents. After polymerisation the amber becomes much less soluble to the extent that polymerised amber will not become sticky when wetted with something such as ether.

Amber is most commonly associated with the orange colour to which it gives it’s name, but amber is also common in yellow, brown and ocassionally green and blue. The blue amber is, as of the time of writing, only found in one place in the world, the Dominican Republic, and called Dominican Blue Amber. Dominican Blue Amber is actually a transparent white colour but when sunlight enters the amber it is refracted within the amber which then emits a blue hue. However, when the amber is viewed under artificial light it looks white.

Baltic amber, which is probably the amber you have seen most of, is almost always the orange colour, and does not change colour like the Dominican Blue Amber. Because amber is so soft, a 2.5 on the moh scale of hardness it is rarely step cut as other gemstones are, but it can still be used in engagement rings. Furthermore most amber has airbubbles inside the amber, these airbubbles affect the light performance of the amber and lead to a cloudy or milky appearance. Milky amber is filled with so many of these airbubbles that when viewed through a microscope resembles sea foam.

Amber is also an incredible preservative, with fully preserved fossils of insects that are at least 60 million years old. Furthermore, scientists have recently extracted the oldest specimen of DNA from amber that was 40 million years old.

Emerald is one of the most popular gemstones, and is a variety of Beryl. It is always green in apperance, or at least it must to be considered a emerald. Although other hues (or colours) are accepted, the majority colour of an emerald must be green. They are a 7.5 rank on the moh scale, which still makes them relatively durable and certainly they are not weak. However, their weakness when compared to moissanite and diamond, and ruby and sapphire makes them fairly useless for industrial use. Furthermore, as a large majorites of emeralds are included, there resistance to breakage is not good.

Because of the large amount of inclusions common in emeralds they are not graded for clarity under magnification, instead a trained eye checks if there are any inclusions. In this way an emerald can be considered flawless if there are no inclusions visible without magnification, even though it is almost certain that the emerald will have many inclusions. Because of this clarity is not normally given too much weight when deciding to buy an emerald or not, although it is certainly important, colour is generally deemed more important.

Emeralds are also frequently treated to enhance appearance with heat-treating to enhance colour, while an oil finish appears to improve clarity and is not frowned upon within the emerald industry as it is for other gemstones. Furthermore, some emeralds are filled with lead glass to further decrease the impact and appearance of inclusions, but this practice is normally frowned upon. Emeralds have found many uses in the jewelry world, whether it be as or engagement rings, they are beautiful alternative that is sure to draw attention.

Our last article was on what many see as a successor or direct challenge to Sapphire, Tanzanite, and this article will explain the basics of the formation of Sapphire and it’s rise in popularity. Sapphire is a variety of Corundum which appears blue, purple, yellow, green or pink. Red varities of Corundum are called rubies and are considered a entirely different gemstone, even though they are the same basic mineral (more on this in another article).

Natural Sapphires can be any of the colours mentioned above, although Sapphire is commonly associated with the deep blue colour, which is usually enchanced due to heat-treating up to 1800C which brights out a slightly deeper colour, much the same as Tanzanite. So widespread is the practice of heat-treating Sapphire that is considered very rare to have an untreated gem, and these are normally supplied with a certificate to certify there is no evidence of treatment.

The colour of Sapphire is measured by three seperate catergories which are Hue, Saturation and Tone. Hue is essentially a value that determines the similarity or difference between one colour and another, and is more simply understood as the basic colour of a Sapphire. Saturation is slightly more complex but is on a simple level, the level of brightness or colour within the basic colour. This can be easily seen on photographs were saturation is adjusted where low saturation will look grey or washed out with high saturation being very vivid and more warm. Tone is similar to contrast in that is measures the difference between two extremes. In this case it is the brightness and darkness of the colour that is evaluated.

Sapphire can also be made synthetically through a process known as the Verneuil process where fine powder is melted and then crystalized into Corundum gemstones such as Sapphires or Rubies. This is increasing useful because of Sapphire’s industrial uses in watches or as electrical insulators. Sapphire is also incredibly hard at 9 on the moh scale (diamond is the hardest at 10), which makes it useful for creating scientific equiptment.