What is a Yellow Emerald?
A yellow emerald is a rare gemstone which has all the same physical properties of a green emerald except for the trace element of iron which causes the color to be yellow instead of green. The green color in green emeralds is caused by trace elements of chromium.
In order to be classified as a “Yellow Emerald” all of the following properties must be present in order to be considered a natural Yellow Emerald™.
Scientific properties:
- Composition: Beryllium Aluminum Silicate with Iron
- Gemstone species: Beryl (same as emerald, aquamarine and morganite)
- Crystal system: Hexagonal
- Class: Cyclosilicate
- Chemical composition: Be3Al2Si6
- Habit: Usually well formed hexagonal prisms
- Mohs scale hardness: 7.5-8
- Cleavage: Imperfect, weak, basal, perpendicular to prism faces
- Tenacity: Brittle
- Toughness: Good; inclusions reduce toughness
- Fracture: Uneven to Conchoidal
- Luster: Vitreous - Resinous
- Streak: White
- Twinning: Twinning is very rare and simple on pyramidal planes
- Specific Gravity: 2.7 (2.65-2.80)
- R.I.: 1.56-1.60; Uniaxial (-)
- Birefringence: Low (0.005-0.009)
- Dispersion: Low (0.014)
- Double refraction: -0.006-0.009
- Dichroism: Yellowish green
- Pleochroism: Weak; greenish yellow to golden yellow
- Transparency: Transparent
- Color: Yellow to deep gold with green hues
- U.V. Fluorescence: very weak to none
- Heat treatment: None to some irradiation
Beryl can come in such colors as green (emeralds), blue (aquamarine), yellow (the more faint yellow varieties are called heliodor), pink (morganite), red (bixbite), and white, though most are colorless (goshenite).
Unlike green emeralds, Yellow Emeralds have far fewer imperfections. Most emeralds are coated with oils to enhance the richness in color and to hide imperfections, but Coughlin Jewelers' Yellow Emeralds are not oiled and are usually flawless to the naked eye.
