SAMSONGEMS >> YOU NEED TO KNOW

COLOR ZONING is a band or a spot of color that is a deeper hue in relation to that of the surrounding material. (Sapphire, amethyst and citrine, frequently show this.)
Bicolored gems will have two or more bands of entirely different colors in the same plane. This is common to watermelon tourmaline and ametrine.

PLEOCHROISM refers to showing more than one color.

DICHROISM is the property of a mineral to show two different colors, or color shades, through two different directions of the crystal. Tourmaline is a good example of this.

TRICHROISM is the ability of a mineral crystal to transmit three different colors, or shades of colors, through three different directions of the crystal. Untreated tanzanite and iolite are good examples or trichroism.
ISOTROPIC minerals show only one color of the spectrum. (This is also possible in colorless gems.)

The Physical Properties of Gemstones

... Specific gravity, or density, refers to how much something actually weigh per size.
... Fewer gems will share the same specific gravity. That makes it one of the most important pieces of information you can have when identifying a gem.

"MOH'S SCALE OF HARDNESS"

... These terms, hardness and toughness, are often misunderstood because their scientific meaning is different than the way they are used in common language. Hardness is defined as the ability to resist scratching and nothing more. The Moh’s Scale is used to define gemstone hardness.

Cleavage
... Cleavage is the tendency minerals have to break or split along the planes of their crystal structure. Some gems also have a direction where they can be easily split and this is the cleavage plane.

Parting
... Parting can be confused with cleavage, as they are nearly identical. Parting also occurs on a flat plane that is parallel to one of the crystal surfaces. The difference is that parting is a result of structural weakness. If a mineral has cleavage, it will exist in every specimen. Parting is only occasionally found and won’t be in every example of a particular species.

Stability
... Stability refers to your gem staying the way that you got it. Most gems are very stable, but that isn’t something you should take for granted because certain factors like heat, chemical sensitivity, light etc do grossly affect the stability of a gem.

BIRTHSTONE LIST

WEIGHTS & MEASURES
CONVERSION CHART