This magical gem appears to be a very fine stone of some sort, but if magic is detected for, its dweomer will be noted. 

When a jewel of flawlessness is placed with other gems, it increases the likelihood of their being more valuable by 100%, i.e., the chance for each stone going up in value increases from 1 in 10 to 2 in 10. 

The jewel has from 10-100 facets, and whenever a gem increases in value because of the magic of the jewel of flawlessness (a roll of 2 on d10), 1 of these facets dis-appears. 

When all are gone, the jewel is a spherical stone of no value.