ADULARESCENCE: An optical phenomenon applied to orthoclase or adulria feldspar that exhibits a floating, billowy, white or bluish light effect.

AGGREGATE: Crystalline aggregate made up of many particles, each of an individual crystal too small to be seen by the unaided eye.

ANTAR-DASHA: Minor planetary period.

ANUKUL: Favorable (Anukula-vad is belief that jyotish gems act same as their ruling planet, therefore gems should only be used for anukul or favourable planetary positions)

BIREFRINGENCE: The strength of double refraction measured by taking the difference between the high and low refractive indices of a doubly refractive gemstone.

CHANDRA-RASI: Moon sign.

CRYSTAL SYSTEM: One of the six groups of crystal patterns in which minerals and other crystalline solids occur. They are : cubic, tetragonal, hexagonal, orthorhombic, monoclinic and triclinic.

CUBIC: Highly symmetrical crystal system with three equal crystallographic axes at right angles.

DICHROISM: The property of doubly refractive colored gemstones of transmitting two different colors in two different directions caused by their unequal absorption of the two portions of a doubly refracted beam of light.

DISPERSION: The property of a transparent gemstone to separate white light into its component colors.

DOUBLE REFRACTION: The property of separating a single ray of light into two.

FLUORESCENCE: The emission of visible light by a gem when exposed to ultra-violet or X-radiation.

GAURA-PAKSHA: The bright fortnight.

HEXAGONAL: A crystal system having three equal axes at 60 degrees and a fourth axes perpendicular to the other three and unequal in length.

INCLUSION: Any internal foreign body or imperfection in a gem.

JANMA-PATRIKA: Sidereal horoscope.

JYOTISH: Vedic sidereal astrology.

JYOTISH-ACARYA: A master-teacher of Vedic sidereal astrology.

KAVACHA: A shield, amulet or talisman.

KETU: The Moon's descending (South) node.

KRISHNA-PAKSHA: The dark fortnight.

KRURA-GRAHA: A harmful planet.

LAGNA: Rising sign.

MAHA-DASHA: Major planetary period.

MANI: Gem or jewel.

MANTRA: A combination of transcendental (Sanskrit) sound vibrations with the power to deliver the mind from material limitations.

MATRIX: The rock in which a mineral is contained.

MOHS SCALE: The most commonly used scale of relative hardness of minerals with numbers from one to ten assigned to ten minerals of increasing hardness from talc to diamond.

MONOCLINIC: A crystal system with two axes unequal in length at right angles to one another and a third axes of unequal length which is not at right angles to the plane of the other two.

NACRE: Pearl substance.

NAKSATRA: Moon constellation (There are 27 constellations).

NAVA-RATNA: The Nine Gems.

OPTIC CHARACTER: The nature of a gem as either uniaxial (singly refractive) or biaxial (doubly refractive).

ORIENT: The iridescent luster of a pearl.

ORTHORHOMBIC: A crystal system with three axes of unequal length, each perpendicular to the plane of the other two axes.

PANCHA-RATNA: The Five Gems.

PLEOCHROISM: The property of most doubly refractive colored gemstones of exhibiting either two or more different colors when observed through a dichroscope in transmitted light.

PRATIKUL: Unfavorable (Pratikula-vad is belief that jyotish gems act OPPOSITE of ttheir ruling planet, therefore gems should only be used for pratikul or unfavourable planetary positions)

RAHU: The Moon's ascending (North) node.

RASI: Zodiac sign.

RATNA: Gem or jewel.

REFRACTIVE INDEX: A measure of the amount a light ray is bent as it enters or leaves a gemstone.

SAPTA-RATNA: The Seven Gems.

SHUKLA-PAKSHA: The bright fortnight.

SUBHA-GRAHA: A helpful planet.

SIDEREAL: Constellational astrology.

SINGLE REFRACTION: When a light ray enters either an isometric or amorphous gem substance, it remains intact and is refracted in the normal manner as a singly ray.

SPECIFIC GRAVITY: The ratio of the weight of a gemstone to that of an equal volume of water at 4 degrees centigrade.

STOTRAM: A Sanskrit prayer and invocation.

TETRAGONAL: A crystal system with two axes equal in length and at right angles with a third axes at right angles to the first two.

TRICHROISM: The property of most doubly refractive, colored gemstones belonging to the orthorhombic, monoclinic, and triclinic crystal systems, of transmitting three different colors in three different directions when observed through a dichroscope in transmitted light.

TRICLINIC: The least symmetrical crystal system with three axes, no two of which are of equal length and no two of which are perpendicular to one another.

TRI-RATNA: The Three Gems.