There are three raw Ethiopian or Welo Opals availble. Please note weight is in carats. These three pieces come from Wollo Province Ethiopia. 
 
A: measures approx. 19 x 13 mm: thickness 7 mm: weight in carats is 7
B: measures approx. 15 x 14 mm: thickness 9 mm: weight in carats is 7.25
C: measures approx. 13 x 11 mm: thickness 6 mm: weight in carats is 4.35
 
Welo Opal or aka Ethiopian Opal is a newer discovery, coming around in 1994. It is considered a precious opal. They tend to be porus so they can be treated. Found in Ethiopia and the color range is Rainbow, Black, White, Orange, Red and Yellow. They have a hardness of 5-6.