Diamond
Color: Colorless, yellow, brown, green, blue, reddish, black
Hardness: 10 Mohs
Specific Gravity: 3.47 - 3.55
Refractive Index: 2.417 - 2.419
In simple word, diamond is carbon. A solid form of carbon with the highest hardness of any natural material on earth. Most natural diamonds are between 1 billion and 3.5 billion years. But only 20% of all diamonds can be used for jewelry, the remaining 80% are used in industry.
How valuable is my diamond?
You'd probably have heard about "4 Cs", they are: color, clarity, cut, and carat (weight). The value of your diamond is measured against these Cs.
The Gemological Institute of America (GIA), has a system of color grading using letters starting at D. The highest quality color grades are D, E, and F.
A clarity grading system also has been devised by GIA. They are: Flawless (F), Very Very Slightly Imperfect (VVSI), Very Slightly Imperfect (VSI), Slightly Imperfect (SI), and Imperfect (I).
Amethyst
Color: Violet, pale red-violet
Hardness: 7 Mohs
Specific Gravity: 2.63 - 2.65
Refractive Index: 1.544 - 1.553
Amethyst is the birthstone of February. It is the most highly valued stone in the quartz group. Amethyst is often associated with bringing luck, ensures constancy, and stability.
Color
You will most probably recognize amethyst from its beautiful purple color. But the gemstone color actually can range from a pale red violet to a deep purple that looks like blue or red. Some amethyst may lose some color in daylight.
Source
Amethyst can be found in every corner of our earth. As mentioned earlier, it is composed of quartz, which is the second most abundant material in the earth's crust. While they can be found anywhere, the most important deposits are in Brazil, Uruguay and the Malagasy Republic.
How to Buy Amethyst
When looking to purchase amethyst, here are some suggested steps:
First, visit a jeweler who is trusted and reputable to ensure that you get the best information about the gemstone.
Second, check the color. A bright deep purple color is most desirable. Avoid white stripes or layers of color, brownish or rust colored tints. Too deep a purple will make the stone look black in certain light condition.
Third, look at the clarity. Visible inclusions will reduce the value of the amethyst.
Since amethyst is relatively abundant, the price usually is inexpensive. Visit our store at 170 Thapae Road, Chiang Mai to view some beautiful and top quality amethysts.
Ruby
Color: Varying red
Hardness: 9 Mohs
Specific Gravity: 3.97 - 4.05
Refractive Index: 1.766 - 1.774
Ruby is named because of its red color. The red color varies with the individual deposits, so it is not possible to determine the source area from the color, as each deposit yields various tones.
The designation "Burma-ruby" or "Siam-ruby" is erroneous, and refers more to quality than origin. The most desirable color is "pigeon's blood", pure red with a hint of blue.
All natural rubies have imperfections in them, including color impurities and inclusions of needles known as 'silk'. We use these needle inclusions in rubies to distinguish them from synthetics. It is extremely common and acceptable now that almost all rubies are treated in some form, with heat treatment being the most common practice.