1. Features of opal in Australia: (1) There are many kinds, including black opal, white opal and crystalline opal, among which black opal is the most expensive; (2) The water content is very stable; (3) relatively thin.

2. Characteristics of African opal: (1) is mainly produced in Ethiopia, mainly producing black opal (mainly dark brown), fire opal, crystal opal, white opal, water opal (opal with strong water absorption and dehydration ability) and so on. (2) The water content is relatively stable and unstable (water opal); (3) The thickness is grotesque. On the left is Opal Australia, and on the right is Opal Africa.

Second, the difference

1, shape: ordinary Australian opal is thinner, and a few parts are thicker (high price); African opal is full and thick, and can be made into various shapes; In terms of size, the opal in Africa is relatively large, and there are few opals below 2ct. Generally, crystal opal is ground into a flat shape, which is determined by the characteristics of opal raw materials.

2. Soaking in water: After testing, all opals have the ability to absorb water, but the opals produced in Africa are stronger and those produced in Australia are weaker. African opal absorbs water faster than Australian opal, and finally does not change color, but changes color after dehydration; However, the water absorption process of Opal Australia is slow, and it will also absorb water and become transparent. Therefore, the color change of Australian opal is more stable than that of African opal;

3, discoloration: Australia Opal discoloration purple, green, blue more, red discoloration is relatively less, mostly single discoloration, less colorful; In Africa, Opal is richer in color, generally changing in red (even in red, orange, yellow, green, blue and purple), with little change in single and double colors; The water opal fire color floats on the surface of the gem, which has a foggy feeling and is not bright, like the light refracted from the surface of soap bubbles. The fire color of the crystal opal is exposed from the inside of the gem, and the color block gives people a bottomless feeling.

4. Color change mode: the rarity of color change mode is: variegated color >; Splash color > spark, the real variegated color, refers to a pattern in which the four corners of a rectangle or a square are put together in a straight line. There are few opal spots in Australia, but there are more sparks. There are many color-changing patterns in Opal Africa, such as filiform, scaly, honeycomb, neon, large flake and so on.