Opal Authenticity Certificate

Certification Standards by MyOpal World

At MyOpal World, we have developed a set of certification standards based on the Australian opal grading system, refined to ensure the highest level of quality and authenticity for every opal we sell.

Weight

Opal weight is measured in carats, with 1 carat equaling 0.2 grams. While larger opals are often rarer, our certification ensures that even smaller opals with exceptional color play are appropriately valued.

Dimensions

We measure each opal’s length, width, and depth to determine its size, influencing its suitability for different jewelry designs. Each opal meets strict dimensional standards at MyOpal World.

Origin

The origin of an opal significantly impacts its value. Our certification ensures that the country or region of origin, such as Australia, is verified for authenticity.

Body Tone (N1-N9 Scale)

The body tone scale classifies opals from N1 (black opal) to N9 (white opal). The darker the tone, the higher the value. Below is a color reference for each grade based on professional gemstone industry standards:

N1
N2
N3
N4
N5
N6
N7
N8
N9

Brightness (B1-B5 Scale)

Brightness is a comprehensive indicator of an opal's fire intensity, density, and color variety. To ensure consistency, brightness is evaluated under specific lighting conditions:

  • **Light Source**: White light with a color temperature of 5000K to 5500K.
  • **Light Intensity**: Between 2000 and 2500 lumens for even illumination.
  • **Observation Distance**: Approximately 30cm (12 inches).
  • **Viewing Angle**: Multiple angles to observe color play.

Brightness levels are classified as follows:

B1 (Very Bright): High density and vibrant play-of-color visible from all angles.
B2: Strong color play with slightly reduced intensity from some angles.
B3: Moderate brightness with less dense fire and color display.
B4: Low density of color play, reduced fire.
B5 (Dull): Minimal color play with weak brightness.

Shape

Opals come in various shapes, each ideal for different jewelry designs. Below are examples of the most common opal shapes:

Fancy Shape Freeform Shape Heart Shape Marquise Shape Oval Shape Pear Shape Rectangle Shape Rose Shape Round Shape Square Shape Trilliant Shape

Dome (Cut)

The dome, or cut, of an opal affects its light reflection and overall appearance. Our standards define dome types as follows:

**High Dome**: Height to width ratio of 0.6 or higher, showing optimal light reflection and color play.
**Medium Dome**: Height to width ratio between 0.3 and 0.6, offering balanced appearance and brightness.
**Low Dome**: Height to width ratio below 0.3, reducing color intensity but maintaining structure.
**Flat Dome**: No significant curvature, usually displaying less vivid color play.

Type of Opal

Opals come in many varieties, each with its unique body tone, transparency, and structure. Below are the key types of opal and their definitions:

  • Black Opal: Opals with a body tone between N1 and N4. Black opals exhibit the most striking play-of-color due to their dark background.
  • Semi-Black Opal: Body tone between N5 and N6. These opals have a medium to dark tone, allowing for good color contrast.
  • White Opal: Body tone between N7 and N9, featuring a light to milky appearance, with softer color play.
  • Crystal Opal: Transparent to semi-transparent opals with body tones between N5 and N9, offering a brilliant play-of-color throughout the stone.
  • Black Crystal Opal: A transparent to semi-transparent black opal, with a body tone between N1 and N4, combining the depth of black opal with the brilliance of crystal opal.
  • Boulder Opal: Opals that naturally form in ironstone, often featuring a dark body tone with visible ironstone backing, enhancing the color contrast.
  • Fossil Opal: Opals formed from the replacement of organic material (such as wood or shells) by opal, creating unique and rare shapes.
  • Fossilized Opal: Similar to fossil opal, but refers to the complete replacement of organic material with opal over millions of years.
  • Doublet: An opal slice bonded to a dark backing, enhancing the stone’s color and giving it the appearance of a solid black opal.
  • Triplet: An opal slice sandwiched between a dark backing and a transparent cap, often quartz, providing additional protection and depth of color.
  • Fire Opal: Usually transparent to translucent, these opals have a bright red, orange, or yellow body tone with or without play-of-color.
  • Boulder Matrix Opal: Opal mixed within its host rock (usually ironstone), with veins of opal running through the stone, offering a striking and natural appearance.
  • Andamooka Matrix Opal: Opal within a porous rock matrix, often treated to enhance color, typically from the Andamooka region in South Australia.