Diamonds History and Shapes Chennai Tamil Nadu , INDIA

AESERA  Jewellery DESIGNING ACADEMY No 144/74, Eskay building, 3rd floor,  Greams Road, Thousand Lights Chennai,  Tamil Nadu India, Mobile: +91-9444100081,+91-9840689781,9840966467 seshu.gopal@jewelrydesignacademy.com Interesting Diamonds facts Diamonds are formed deep within the Earth: between 100 km and 200 km below the earth's surface. Diamonds form under remarkable conditions. The temperatures they are formed at are about 900 - 1300 C in this part of the Earth's mantle where diamonds form. The pressure is between 45 - 60 kilo bars. (kB) 50 kB = 150 km or 90 miles below the surface 60 kB = 200 km or 120 miles below the surface. Diamonds are carried to the surface by volcanic eruptions. The volcanic magma conduit is known as a kimberlite pipe or diamond pipe. We find diamonds as inclusions in the (rather ordinary looking) volcanic rock known as kimberlite. The kimberlite magmas that carry diamonds to the surface are often much younger than the diamonds they transport (the kimberlite magma simply acts as a conveyer belt). To ensure they are not converted to graphite, diamonds must be transported extremely rapidly to the Earth's surface. It is probable that kimberlite lavas carrying diamonds erupt at between 10 and 30 km/hour (Eggler, 1989). Within the last few kilometers, the eruption velocity probably increases to several hundred km/hr. All natural diamonds are at least 990,000,000 years old. Many are 3,200,000,000 years old (3.2 billion years) how do we know this? Age: from Carbon dating? No! C-dating only works for very young carbon. You need to use other radioactive decay schemes (e.g., uranium-lead) to date inclusions in diamonds. Inclusions used for dating are around 100 microns in diameter (0.1 mm). Diamond is the hardest material Diamond is the hardest gem on the Mohs hardness scale and graphite (also made from carbon atoms) is the softest! The rating of a mineral's "Hardness" or resistance to being scratched can be given using Mohs' scale. This was devised by the German geologist Frierich Mohs (1773-1839). Rating Type mineral Everyday equivalent 1 Talc Baby powder 2 Gypsum fingernail 3 Calcite bronze coin 4 Fluorite iron nail 5 Apatite glass 6 Feldspar penknife blader 7 Quartz steel knife 8 Topaz sandpaper 9 Corundum 10 Diamond Given that both diamond and graphite are made of carbon, this may seem surprising. The explanation is found in the fact that in diamond the carbon atoms are linked together into a three-dimensional network whereas in graphite, the carbon atoms are linked into sheets with very little to hold the sheets together (thus the sheets slide past each other easily, making a very soft material). How rare are diamonds? How many grams do you need to mine to get 5 grams of diamonds? (5g/1000 kg) @ 1000 g/kg = 5 g /1,000,000 g! But only 20 % are gem quality (80 % of these are sold in a "managed selling environment") and the remainder are used for industrial purposes (this material is known as "bort" or "carbonado" (carbonado is finer)). Basic Data Hardness = 10 Crystal System = cubic Refractive Index = 2.42 Dispersion = 0.044 Specific Gravity = 3.52 Treatments and synthetics Fracture filling of cracks and removal of inclusions. Surface cracks fractures and cleavages reaching the surface can be filled with a glass-like material with similar RI.. Identification: when examined with an optical microscope, filled stones will show: greasy appearance, flash effects, bubbles. Problem: Filling does not always resist polishing, heating, cleaning, age wear and tare Drilling of inclusions involves using a laser to drill into the inclusion. Solutions can be poured into the resulting "hair-width" diameter hole to bleach colored inclusions. This is compared to getting a filling in your tooth. Irradiation is used to change the color of the diamond. A common color produced by irradiation are greens yellow and blues, usually very intense and not natural looking. Synthetic diamonds are often yellowish in color (rarely used for gem purposes, more commonly used as diamond grit for industrial purposes. Modern synthesis of thin film diamond has other industrial applications). A 5 mm diamond (0.5 carat) takes over a week to grow. Synthesis requires: high pressure high temperature a special apparatus Synthetic diamonds can sometimes be distinguished from natural diamonds by the presence of flux inclusions (Ni, Al or Fe). Simulants - That try to simulate the appearance of diamond The distinction between a synthetic diamond (man-made diamond consisting of carbon atoms arranged in the typical diamond structure) and a diamond simulant (not a carbon compound with the diamond structure) is very important! In order of increasing R.I., the most common simulates are: YAG = yttrium aluminum garnet GGG = gadolinium gallium garnet CZ = cubic zirconia Strontium titanate Diamond. Another diamond stimulant is synthetic moissanite (Silicon carbide or carborundum) it was introduced to the jewelry market in 1998 it is one of the better simulates to date, but displays double refraction and may turn yellow under the heat of a low flame. Diamond Shapes Brilliant Cut: Shape Round from top view The most popular of all cuts the brilliant in its Ideal proportions is designed to give maximum scintillation, beauty and fire. It is comprised of 58 facets; the Brilliant cut follows more naturally the rough diamond crystal shape, and thus is most popular for cutting due to the beauty it returns, please see proportions for a complete explanation of why proportions for a round brilliant are so important for beauty and price. Princess Cut: Shape is square from top view The princess is one of the most popular fancy diamond shapes. The proportions are considered better the more square the stone is cut, with exact 90 degree internal angle on each corner; princess cut diamonds can also be slightly rectangle in shape. Optimum Shape is: Length to Width ratio 1:1 Acceptable are: Length to Width ratio 1-1.4:1 Oval Cut: Shape elliptical from top view The oval cut is also a particularly beautiful shape and if well proportioned gives great scintillation and fire. A well cut oval diamond can be almost as bright as a well cut Brilliant or round shaped diamond as the angles for cutting are closer to that of a brilliant cut diamond. Optimum Shape is: Length to Width ratio 1.5:1 Acceptable are: Length to Width ratio 1.5-1.75:1 Heart Cut: Shape is Heart from top view The heart shape is one of those special cuts that follow more human and emotional values. The technical benefit is that a heart shape diamond has a roundish pavilion and if well cut and proportioned can drive the sparkle and scintillation back out of the diamond. Optimum Shape is: Length to Width ratio 0.9-1.2:1, or which is most pleasing to the eye Marquise Cut: Shape Marquise of football shape top view The Marquise is a slender striking cut if well proportioned popular for up market designer pieces. The shape lends it self to being visually bigger with a bigger table spread for carat weight than traditional cuts, it has a line of beauty that can be used running up and down the finger. Optimum Shape is: Length to Width ratio 2:1 Acceptable are: Length to Width ratio 1.75-2.25:1 Emerald Cut: Shape like a rectangle with corners cut off, top view The Emerald Cut is a very bold and sold feeling cut. The Emerald cut uses a series of flat rectangular facets stepping down off the table to give it a unique brilliance, quite different to that of a Round or curved shaped cut. Optimum Shape is: Length to Width ratio 1.35-1.65:1 Acceptable are: Length to Width ratio 1.25-1.75:1 Trilliant Cut: The shape is like a triangle top view One of the more unusual cuts the trilliant displays a very sharp brilliance or fire if the diamond is cut to the correct depth allowing good scintillation. Excellent for Shoulder diamonds accompany a square or rectangular shaped diamond. Optimum Shape: Length to Width ratio 1:1 Acceptable are: Length to Width ratio 1:1 Pear Cut: The Shape is Pear top view The pear is another popular fancy cut it uses the base of a brilliant or round cut and extends it self to point , if well proportioned it gives a depth of scintillation to the point of the stone. A benefit in design if a longer look is required. Optimum Shape: Length to Width ratio 1.5:1 Acceptable are: Length to Width ratio 1.5-1.7:1 Radiant Cut: Similar to a rectangle or square with the corners cut off top view The Radiant can either be cut as a square or rectangle. The Radiant has a strong look with a unique type sparkle, differing from Emerald and Princess Cuts. Optimum Shape; For Square Length to Width ratio 1:1 Acceptable are; For Rectangle Length to Width ratio 1.5:1 Curved Trilliant Cut: Rounded Trilliant top view A softer look than the straight edge trilliant , a more unusual cut for a diamond , a bold fattish looking shape, deep and strong appearance , three soft points, three lines of curvature , nice if well proportioned. Optimum Shape: Length to Width ratio 1:1 Acceptable are: Length to Width ratio 1.1 to 1 Baguette Cut: Rectangle shape top view Coming from the French bread stick. The Baguette may be Cut long or more emerald shaped in proportions. As a main stone the proportions should be more like a rectangle shape. The Baguette is for those people who want a long stone, usually used are small baguettes to accompany different shaped diamonds. Unusual in Larger sizes. Optimum Shape: Length to Width ratio 1.5:1 Acceptable are: Length to Width ratio 1.5.-2.5:1 Tapered Baguette Cut: Rectangle shape or Tapered Rectangle top view Coming from the French bread stick. The Baguette may be Cut long or more emerald shaped in proportions. As a main stone the proportions should be more like a rectangle shape. The Baguette is for those people who want a long stone, usually used are small baguettes to accompany different shaped diamonds. Unusual in Larger sizes. Optimum Shape: Length to Width ratio 1.5:1 Acceptable are: Length to Width ratio 1.5.-2.5:1 Asscher Cut: Top view can be square to rectangle with an octagon eight sided look, the more square the better, but in some cases a longish stone can have a great beauty. Joseph Asscher was an eminent diamond cutter who cut the 3,106 carat Cullinan diamond. Asscher worked in Amsterdam. In 1902, his company, the Asscher Diamond Co., developed and patented the Asscher cut, a squarish step cut with an almost octagonal outline. This new cut enhanced the fire and light of the stone; it had a small table, a high crown, wide step facets, a deep pavilion and square culet. This cut became very popular in Art Deco jewelry and was a forerunner of the emerald cut. Recently, the Royal Asscher Diamond Co. resumed production of the original Asscher cut diamonds. Optimum Shape: Length to Width ratio 1:1 Acceptable are: Length to Width ratio 1-1.4:1