You are, of course, aware that many Eastern gems are credited with hypnotic powers.

This one undoubtedly has them." As he spoke he drew out the emerald, and held it by the clasp under a cluster of electric lights.
"What a glorious gem!" exclaimed the Prince, starting forward to look at it more closely.

"There is nothing to compare with it even among the Imperial jewels of Russia." "Have a care, Highness," said the Egyptian, raising his left hand, "unless you wish to fall under its influence.

Once it seized your gaze you could not withdraw it without the permission of its possessor, and meanwhile he would have complete mastery of you.

I am your faithful servant, and therefore I warn you." Was there just the faintest suspicion of a sneer in his voice as he said this?
If there was, Oscarovitch did not notice it.