Emerald Diamond Jewellery Ring

Emerald Diamond Jewellery Ring 

Emerald

Béryl var. émeraude sur gangue (Muzo Mine Boyaca - Colombie) 2.jpg

Emerald crystal from Muzo, Colombia

General

Category Beryl variety

Formula

(repeating unit) Be3Al2(SiO3)6

Crystal system Hexagonal (6/m 2/m 2/m) Space group: P6/mсc

Space group (6/m 2/m 2/m) – dihexagonal dipyramidal

Unit cell a = 9.21 Å, c = 9.19 Å; Z = 2

Identification

Formula mass 537.50

Color Green shades to colorless

Crystal habit Massive to well Crystalline

Cleavage Imperfect on the [0001]

Fracture Conchoidal

Mohs scale hardness 7.5–8

Luster Vitreous

Streak White

Diaphaneity Transparent to opaque

Specific gravity Average 2.76

Optical properties Uniaxial (−)

Refractive index nω = 1.564–1.595,

nε = 1.568–1.602

Birefringence δ = 0.0040–0.0070

Ultraviolet fluorescence None (some fracture-filling materials used to improve emerald's clarity do fluoresce, but the stone itself does not)

References 

Emerald is a gemstone and a variety of the mineral beryl (Be3Al2(SiO3)6) colored green by trace amounts of chromium and sometimes vanadium. Beryl has a hardness of 7.5–8 on the Mohs scale. Most emeralds are highly included, so their toughness (resistance to breakage) is classified as generally poor. Emerald is a cyclosilicate.