Black abacus ring
Jadeite comes in black too. It gains in popularity in recent years. However, this ring is not totally black like onyx. It has small white patches and has good lustre. The ring size is 16 and it is 6.2mm broad.
As the size is fixed, Chinese believe that each jade ring is meant only to one who has affinity to it.
The size used above is for China/Hong Kong/Japan.