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Buying a diamond might seem difficult, but it isn't difficult if you have the right evaluation criteria. For your use, we describe here about various tools, so you can learn all about diamonds to evaluate your needs exactly what you want to purchase.
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Four Factors - known as the Four Cs affect the value of every diamond :
Clarity characteristics are classified as inclusions (internal) or blemishes (external). The size, number, position, nature, and colour of inclusion or blemishes determine the clarity grade. Very few diamonds are flawless, it means there is not shown any inclusions or blemishes when examined by a skilled person under 10x magnification. flawless stones are most expensive
Grading colour in the normal range involves deciding how closely a stone's body colour approaches colourlessness. Most diamonds have at least a trace of yellow, brown body colour. With the exception of some natural fancy colours, such as blue, pink, purple, or red, the colourless grade is the most valuable.
Cut means the proportions and finish of a polished diamond. Proportions are the size and angle relationships between the facets and different parts of the stone. Finish includes polish and details of facet shape and placement. Cut affects both the weight yield from rough and the optical efficiency of the polished stone. A successful cutter is who achieve best optical efficiency with highest weight of diamonds after cutting from rough diamonds.
Carat Weight
The metric carat, which equals to 0.200 gram, is the standard unit of weight for diamonds and most other gems. If other factors are equal, the cost of the diamonds increases with the weight increasing.
Hue: Pure, spectral (prismatic) colour. Hues include gradations and mixtures of red, orange, yellow, green, blue, violet, and purple.
Tone: A colour's position on a colourless-to-black scale.
Saturation: A colour's position on a neutral-to-vivid scale.
Fancy diamond: A diamond with an attractive natural body colour other than light yellow, light brown, or light gray.
Treated diamond: A diamond with body colour bodycolour induced by some form of artificial irradiation, often in conjunction with controlled heating (known as annealing).
Coated diamond: A diamond coloured by a surface coating which masks the body colour bodycolour; the coating may be extensive (entire pavilion, for example), but is more often limited to one or two pavilion facets or a spot on the girdle.
Detecting Treated Diamonds
Treatment Clues: Even, medium to dark, vivid green, blue-green, or blue body colour.
Treatment Proofs: Umbrella effect, coloured pattern following facet junctions, coloured ring around the girdle (green, yellow, brown, pink); radioactivity (radium green); brown, disc-like inclusions (radium green); fogs photographic film (radium green); electrically non-conductive (blue); 592 nm absorption line (green, yellow, most brown, pink).
Natural Clues: Darker green or brown naturals or surface spots (light green, brown).
Natural Proofs: Electrically conductive (blue).
When in doubt, always submit coloured diamonds to GTL for an origin of colour report.
Detecting Coated Diamonds
Examine the surface under high magnification (45x or more) in diffused or reflected light. Pay particular attention to areas near the girdle. The coating may have tiny pits or bubbles, and may be scratched with a probe; an orange filter may help. Other clues include subnormal brilliance and dispersion, an iridescent sheen or a lack of transparency when viewed table-down in the DiamondLite, or an odd look when compared to masterstones.
Use the colourMaster to:
Create objective colour descriptions
Establish reliable price comparisons
Make exact records of coloured diamonds, bought, sold, or appraised
Communicate more effectively and confidently with suppliers
Diamond's cleavage produces step-like breaks like the one seen near the girdle of the round brilliant; a piece of glass shows the smooth, curved fracture surface typical of simulants.
As is the case with most gem materials, diamond has various physical and optical properties which can be measured very precisely by a trained person with the right equipment. Here are some of its important identifying properties and characteristics:
Refractive index (RI): 2.417
Dispersion: .044
Luster: adamantine
Transparency: exceptional
Specific Gravity (SG): 3.52
Hardness: 10 on Mohs scale
Toughness: good in cleavage directions; otherwise exceptional
Cleavage: four directions, perfect
Fracture: step-like (alternating straight cleavages and conchoidal fractures)
Included crystals: angular ones are unique in type and appearance
Polish: superior (best possible)
Facet edges: sharp (typically)
Girdle: normally waxy to granular; bearding common
Naturals: show characteristic growth markings
Spectra: positive identifying absorption lines at 592, 504, 498, 478, 456, and 415 nm
Wetability: difficult
Thermal inertia: highest of any substance
Response to X-rays: transparent; almost always fluoresces blue
General Characteristics of Simulants
Although you can normally separate any diamond simulant from diamond simply and reliably with the diamond thermal tester, there are a number of other characteristics that expose various simulants for what they are. Here are some of the more obvious ones:
All common diamond simulants (except some glass and some doublets) have higher SGs than diamond.
Only synthetic rutile, strontium titanate, and CZ have significantly higher dispersion than diamond.
Man-made stones may contain gas bubbles.
Like diamonds, many common simulants do not give a reading on standard refractometers (over the limits); but synthetic sapphire, synthetic spinel, most glass, and some doublets do.
Synthetic rutile, zircon, and synthetic sapphire are doubly refractive; diamond is singly refractive.
Simulants with RIs below that of strontium titanate can have a read-through effect.
For more information on Diamonds and their prices,
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