"A gem, in order to be a gem and valuable, has to have beauty, rarity and durability." It was the first sentence uttered by my teacher, Michael O'Donoghue, when I began my formal gemological studies. Which brings me to the subject of spinel. I don't know why, but in the early days, like most gem dealers I never thought much of them. But over more than a decade, and especially after several close encounters with spinels in Mahenge, Tanzania, I have become totally enchanted by the gemstone.