[et_pb_section fb_built=”1″ _builder_version=”4.16″ global_colors_info=”{}”][et_pb_row _builder_version=”4.16″ background_size=”initial” background_position=”top_left” background_repeat=”repeat” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ custom_padding=”|||” global_colors_info=”{}” custom_padding__hover=”|||”][et_pb_text _builder_version=”4.27.4″ background_size=”initial” background_position=”top_left” background_repeat=”repeat” hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n
Gemology – Terms explained<\/strong><\/p>\n In my work, I frequently use terms derived from gemology. When assessing the quality of gemstones, people often talk about the four Cs: Cut, Colour, Clarity<\/strong> and Carat<\/strong>. Cut<\/strong> Colour<\/strong> Clarity<\/strong> Carat (carat weight)<\/strong> Gloss<\/strong> Refractive index<\/strong> Dispersion<\/strong> Transparency<\/strong> Double-break<\/strong> Crystal Structure<\/strong> Chemical composition<\/strong> Crystal shapes<\/strong> Natural cluster<\/strong> Hardness<\/strong> By comparison:<\/p>\n Talc has a hardness of 1<\/strong><\/p>\n<\/li>\n Moonstone round 6<\/strong><\/p>\n<\/li>\n Sapphire 9<\/strong><\/p>\n<\/li>\n Diamond 10<\/strong><\/p>\n<\/li>\n<\/ul>\n The higher the number, the more resistant the stone is to scratching. Cleavage<\/strong> Fracture<\/strong> Inclusions<\/strong> Natural gemstone<\/strong> Lab-grown diamond<\/strong>
On this page, I explain them in a simple way so that you can better understand what I am talking about in my blogs and in the descriptions of my jewellery.<\/p>\nThe 4 Cs<\/h3>\n
These four properties tell a lot about the quality and appearance of a gemstone.<\/p>\n
The way a gemstone is cut and polished. The cut determines how light reflects off the stone and how much brilliance you see.<\/p>\n
The hue, intensity and evenness of color. With many gemstones, that very color is what makes them so recognizable and beloved.<\/p>\n
The degree to which a gemstone is free of inclusions or minor blemishes. Some gemstones are completely clear; others contain natural inclusions that tell something about their origin or formation. Both are perfectly normal and say something about the unique origin of the stone.<\/p>\n
The weight of a gemstone. One carat is equivalent to 0.2 grams.
Merchants used to weigh gemstones with a balance scale, using the seeds of the carob tree as a measure of comparison. Those seeds remarkably often weighed the same amount, making them ideal as natural standards. The average weight – about 0.2 grams per seed – was later recorded as one carat.<\/em><\/p>\nAbout optical properties<\/h3>\n
The way a gemstone’s surface reflects light back. Think glass gloss, silk gloss or metallic gloss. Each gemstone and pearl has its own luster.<\/p>\n
When light enters a gemstone, it changes direction. How strongly that happens is called the refractive index. The higher the refractive index, the more brilliance a stone shows. You can compare it to a straw in a glass of water: it suddenly appears “broken” or shifted, because the light changes direction as soon as it enters the water.<\/p>\n
Dispersion means that white light breaks up into rainbow colors. You can see this especially in diamonds, where the light “dances” in flashes of red, blue and yellow. It creates that irresistible “magpie effect” that has enchanted us for centuries.<\/p>\n
Transparency indicates how much light a gemstone lets through – from completely transparent to completely opaque. For example, a diamond or tourmaline is transparent, a moonstone semi-transparent (also called translucent) and a lapis lazuli completely opaque.<\/p>\n
In some gemstones, such as tourmaline, light is split in two directions. This makes the stone appear extra vibrant.<\/p>\nOn structure and composition<\/h3>\n
Every gemstone is made up of tiny building blocks: atoms. The way those atoms are arranged is called the crystal structure. You can think of it as a kind of repeating pattern, like the bricks in a carefully bricked wall.
For example<\/em>, diamond and graphite both consist of carbon, but the atoms are arranged very differently. As a result, diamond is rock hard, while graphite is soft and black.<\/p>\n
What is literally in a gemstone. Like a recipe, each gemstone consists of specific “ingredients. Thus, ruby consists of aluminum and oxygen, with a little chromium that provides the red color.<\/p>\n
The natural form in which a gemstone grows. This can be cubic, hexagonal or elongated, for example.
You’ve probably seen it in a gem or mineral store: those rough “chunks” with straight surfaces or tapered points. These are crystals in their natural form, even before they are cut or polished.<\/p>\n
When several crystals grow together, we call it a cluster. You can think of it as a group of crystals growing up from one “root” or base, often in different directions. In quartz or amethyst, you can see this very well: dozens of tiny crystal points that together form a whole – like flowers growing from the same stem.<\/p>\n
Indicates how well a gemstone resists scratching. This is measured on the Mohs scale<\/strong>, which runs from 1 (very soft) to 10 (the hardest).<\/p>\n\n
So a sapphire is hard enough for daily wear, while a moonstone is a bit more sensitive and requires more care.<\/p>\n
The tendency of a gemstone to fracture in certain directions. That has to do with how the atoms in the stone are arranged: along those natural lines, a stone can split more easily. Not every gemstone has an obvious cleavage, but in some – such as topaz or diamond – it is easy to see. Therefore, grinders must work extra precisely with such stones, because one wrong stroke can cause the stone to break in two.<\/p>\n
The way a gemstone breaks if it does not go along its natural cleavage direction. Whereas fission<\/em> proceeds neatly along straight lines, fracture<\/em>, on the contrary, is more erratic and less predictable. (and somewhat the “fear” of any goldsmith who is setting a gemstone. one wrong action and the gem breaks…). Quartz, for example, has no cleavage and breaks with smooth, round shapes – this is called a shell fracture. You can compare it to how a piece of glass breaks: smooth, but with slightly curved lines.<\/p>\n
Small imperfections or natural marks in a gemstone. Sometimes they are actually beautiful to see: a tiny world that tells something about how and where the stone was formed. To gemologists, inclusions are often like fingerprints – unique and recognizable. They may say something about the origin of the stone, or, on the contrary, confirm that it is natural. And sometimes they only make a gem more fascinating.<\/p>\nOn origin and treatment<\/h3>\n
A natural gemstone is created in nature, without human intervention. That formation can take millions of years, deep inside the earth under high pressure and temperature, or just at the surface due to cooling of minerals. No two natural gemstones are exactly the same: slight differences in color, inclusions or growing conditions make each stone distinctive and contribute to its own appearance.<\/p>\n
A lab-grown diamond is one that was not formed deep in the earth, but in a laboratory. There, natural conditions are mimicked: high pressure and temperature allow carbon to crystallize into diamonds. The chemical composition, hardness and brilliance are exactly the same as that of a natural diamond. Only specialized laboratories can (unfortunately) determine the difference.<\/p>\n