Appraisal Process

“After all, it is no easy matter to define a precious stone. Where can the line be drawn between stones that are precious and stones that do not merit that appellation?

Yet there is something to be said in favour of the high position commonly given to the diamond, the ruby, the emerald, the sapphire, and we may add the pearl and the opal: they all possess a very conspicuous and obvious beauty. By brilliancy and colour they force themselves upon our attention…

Diamond, ruby, emerald, sapphire, pearl, opal ; opal, pearl, sapphire, emerald, ruby, diamond – such is the range and variety of acknowledged gems.

~A. H. Church, M.A. Oxon, F.C.S., F.I.C., Professor of Chemistry in the Royal Academy of Arts

Historically, precious gems have been difficult to value for a variety of reasons – mainly due to their inherent uniqueness. Beauty, durability and rarity have always been definitive characteristics of gemstones – but methodology has evolved in order to better appraise precious gemstones in a more deliberate and accurate manner.

Opals are classified and typically have more value based on a darker body tone, intense colour play, strong radiance, the spectral range of colour and the weight – i.e. the carats.

The Andamooka Opalstone exhibits a unique and brilliant combination with the following characteristics:

  • Black (N1-N4) Body Tone
  • Exceptional Colour Play
  • Strong Radiance
  • Wide Spectral Range
  • Rich Contrast Pattern

12 Analytical Steps in Order to Arrive at a Final Appraisal:

1 . Body Tone

  • BL, Black Body (N1 – N4 Tones)
  • DR, Dark Body (N5 – N6 Tones)
  • LT, Light Body (N7 – N9 Tones)
  • CR, Crystal Body (N7 – N9 Tones)

2. Spectrum

  • X1 – Extra Wide Intense: Strong radiance and exceptional colour play in a wide spectral range. Splashes fill over 90% of the body. Rich, contrast pattern.
  • X1_RO – Red-Orange shift: Strong radiance and exceptional colour play with a dominance of red, orange and yellow hues. Splashes fill over 90% of the body.
  • X1-GG – Green-Gold shift: Strong radiance, intense colour play with a dominance of green and warm yellow hues. Splashes fill over 90% of the body.
  • X1-GB – Green-Blue shift: Strong radiance, intense colour play with a dominance of green, blue and violet hues. Splashes fill over 90% of the body.
  • X2 – Wide Intense: Good radiance and wide colour play with a single hue prevailed. Splashes fill over 70% of the body. Sharp, distinct pattern.
  • X3 – Evident: Moderate radiance and reduced colour play. Splashes fill over 50% of the body.
  • G1 – Vivid Grain: Strong radiance and colour play. Splashes fill over 70% of the body. Sharp granular or pinpoint patter.
  • G2 – Dim Grain: Moderate radiance and reduced colour play. Splashes fill over 50% of the body.
  • PP – Poor: Poor radiance with scanty colour play.

3. Shape

  • Oval or round cabochon
  • Fancy cabochon
  • Prolate cabochon
  • Freeform
  • Other

4. Specific Body Tone

  • N1 – N9

5. Brightness

  • 1-7

6. Pattern

  • Ribbon Pattern
  • Floral Pattern
  • Chinese Writing
  • Flagstone Pattern
  • Chaff Pattern
  • Broadflash Pattern
  • Rolling Mackerel
  • Harlequin Pattern
  • Ribbon Mackerel
  • Pinfire or Pinpoint

7. Polish – Confirm Finish

  • Exceptional
  • High
  • Standard
  • Poor

8. Stone Thickness

  • Well Domed
  • Flat
  • Low Domed

9. Display Area

  • Double-Side Polished
  • Single-Side Polished

10. Imperfections Identification

  • Cracks
  • Crazing
  • Inclusions
  • Sand
  • Gypsum
  • Potch

11. Stone Cut

  • Good
  • Average
  • Poor

12. Overall Impression

  • Special Characteristics
  • Interesting Attributes
  • Faults

That said, ultimately there is no litmus test for discovering your perfect opalstone. However important each of the above classifications is, at it’s heart choosing the perfect opal is an emotive process.

This is what we consider the beauty of opals as each one, even moreso than the other precious gems, is dramatically unique.