What is a Diamond - is a mineral of carbon that is crystallized in an isometric arrangement and is born hundreds of miles below the earth’s surface.
Knowing Diamond First
OPTICAL PROPERTIES OF A DIAMOND
- BRILLIANCE– the flash of white light that plays inside the stone (internal reflection) and reflects off on the surface (external reflection). If pavilion angle and depth are correct, brilliance is achieved. If Pavilion is deep and shallow some light will be lost through the pavilion.
- DISPERSION– also called as FIRE, it is the breaking up of white light into spectral colors and takes along crowns height are correct. If both are either higher or shallow, dispersion will be lessens.
- SCINTILLATION– also called SPARKLE and refers to the movement of those colors (dispersion) and brilliance of the stone. This only happens when the stone, the light source and the observer moves.
PHYSICAL PROPERTIES OF A DIAMOND
- HARDNESS - Resistance to scratches. Rank as 10 in the MOH’s hardness scale. Hardest substance known to man
- TOUGHNESS - Resistance to chipping and breaking. Good in cleavage direction.
- STABILITY - Resistance to chemical breakdown, heat, temperature change and fading
CHARACTERISTICS OF DIAMONDS
- Cold to touch just like any other natural gemstone
- A good conductor of heat, which electrifies when rubbed
- Unattached by any acid. It suffers thermal but at as temperature of 2900F. Without any air it turns into graphite with air vaporizes. The process is irreversible.
- It suffers a thermal shock. (stress caused by temperature change, often resulting in fracture)
- Hardest among all known gemstones.
- Transparent to x-ray.
HOW TO APPRAISE A DIAMOND
To examine stone for clarity you need:
- 10 power magnifier or loupe and fluorescent lamp
- When using a 10-power loupe, hold it ½ to 1 inch away from the stone bring into focus, keeping both eyes open.
- The closer the loupe is to your eyes, the greater your field of vision will be.
Clean the stone (diamond) by rubbing it with a lint-free cloth. Avoid touching the stone with your fingers (it leaves smudges)
- Examine the entire stone with your naked eye (one of the criteria for assigning clarity grades is the visibility of the diamond.
- Hold the diamond face up and with a 10-power loupe. Examine the stone from various angles – top – bottom – sides.
- Look at the stone with light shining on it from various angles.
- Assign clarity grade base on the clarity scale and color.
- Measure the diamond from girdle to girdle.
- Value the stone based on the company’s standard diamond valuation.
- (Note: Diamond valuation for carat in “between” standard valuation will be based in the lower carat. E.g. 0.04 based on 0.03; 0.11 based on 0.06 not to 0.12).