WOBM-1oz and WOBM-2oz: The “B” grade stones we are selling range from 2-6 grams each and are nugget-like stones with a small amount of matrix on some pieces. This material is not quite as bright as “A” grade opal with less yield…but this is still good cutting material in it’s own right. Approximately 6-10 pieces to the ounce. More photos available upon request. The opal shown here is a picture of a 1 kilo assortment of stones taken from this Welo opal grade. One and two ounce lots of this opal grade.