How To Buy Opal
Some basic factors to consider when buying Opal
- Fire type: harlequin (which type?), flash, broadflash, large or small pin, combinations, or?
- Colors: red (which type, magenta, etc.), green, blue, purple, gold, etc. predominance, combinations.
- Base color: black, grey, degree of blackness, crystal, jelly, white,off-white, yellow, brown, etc.
- Thickness of the color bar, consistency all around the piece, interplay of the various color bars, top or side cutting.
- Brilliance.
- Equipment, etc: High speed, low speed, diamond vs Carborundum. How you handled the opal when grinding. Heat and amount of water used in cutting.
- Your skill: hobbyist, beginner, intermediate, expert, designer, dealer.
- What you want to do with the opal: standard cabs, free form, inlay, composites, doublets, triplets.
- Source: fields, depth of mining, methods of mining: Buy nothing from New Field at Coober Pedy area or Mehi at Lightning Ridge. It helps to know your supplier.
- Storage and transport methods: (Safe deposit boxes are not safe for opal when left dry. Call for an explanation.)
What follows is the primary factors in determining the value of rough opal... but there's a lot more to this than meets the eye! We've also included a text file that you can download and take with you to the next gem show you attend. This will explain a lot of terminology and help you understand why certain properties are valuable and others are not.
Click here to download the Opal Buying Guide
 |
| FACTOR | DESCRIPTION | VALUE |
| Base Color and Degree of Translucence |
White
or Jelly (opaque) |
 |
| Fire Color | Green Blue Blue-Green Red-Green Multicolor (3, 4, or 5 colors) Red predominant, multicolor Magenta and True Purple (very rare) |
|
| Fire Pattern |
Sunflash Broad rolling flashes |
|
| Fire Intensity |
Very directional with
dead areas High intensity |
|
 |
| FACTOR | LEAST VALUABLE | MOST VALUABLE |
| Quality
of fire band in rough |
Thin (triplets, dome cabs) |
(high domed or flat stones) |
| Penetration | Partial
penetration of fire band |
|
| Waste | Little
fire in relation to waste - spare fire, large waste |
|
| Straightness | Fire band not straight or poor shape of rough relative to band |
|
| Intensity | Fire intensity muted or not bright |
|
