Black opals as pairs are very rare and hard to gete exact even match.
LIGHTNING RIDGE OPAL – Lightning Ridge is a town in New South Wales, Australia.
Black Opals were first discovered and mined in this area.
Black Opals that are found in Lightning Ridge are the most beautiful gemstones
with exceptional quality and brilliance in colors.
The most sought after opals are the ones with the most vivid, brilliant and deepest
and strongest of the colors of the rainbow.
Black opals are rare and and formed individually so some matching pairs might have higher dome or more colour fire than its sister stone
Black opals are formed in Nobbys or in seam opal
If it is seam opal it is easier to cut matching opal pairs but most seam opal does not have a cabochon and is flat. most seam opal is not a dark a s black opal Nobbys
Black opals formed in Nobbys are more black colour but very hard to get matching pair a s if knobby is cut into two ,one piece is always brighter than other.
Fortunately the ears are spread part so slight variance in black opal is passable for wearer.
Black opal pairs are mostly set in 18k gold and if commercial grade opal they are set in sterling silver earrings