Buy Matrix opal rough direct from miners. Matrix is a generic term used to describe opal that has formed mixed in its parent rock instead of the opal forming on top of the parent rock.
The opal is infused inside the rock so with boulder it is in the ironstone and for opal fields in Andamooka it is infused in the sandstone potch. These are the two main opal fields in Australia but also opal from Honduras can also be called Honduras black opal matrix
As the opal forms in all the rock specimen they have been popular to make beads so most opal beads today are cut from boulder matrix.
When buying rough matrix it is still difficult to determine how far the colours will run inside the rock ,as some are formed like kernel and all rough has colour but others are just skin deep or just one part of the opal has color veins.
If cutter needs to cut beads its best to make square shape and use bead cutting machine to shape round as by hand it is difficult to correctly shape .most matrix will cut good cabochon opal stone so are ideal for large men’s rings and veins of colour in deep ironstone does look masculine in appearance. The darker the ironstone the better the polish but these opals are tough on saw blades and cutting wheels so we recommend thick saw blades a s thin saw blades s bend to easy when they get stuck in this ironstone matrix