A noble lady and an unscrupulous master.

A noble lady owned a cross adorned with large diamonds. She didn’t know how many diamonds there were, nor was she interested in knowing, because she was fascinated by another feature of the cross: no matter which of the three upper ends she started counting from, she always ended up with the number nine when she reached the base of the cross.

The cross needed repairs, so the lady informed the jeweler about this unique feature. “You see! No matter which ends I start counting from, it always totals nine! This is how I ensure all the stones are accounted for,” she explained.

“Just like that?” the jeweler asked.

“Yes, just like that. It’s quite sufficient. I will check the number of stones the same way after your repair,” she replied.

The jeweler, however, was unscrupulous. He removed and kept two diamonds, then altered and repaired the cross before returning it to the lady. She counted the stones in her usual manner and found that all the stones appeared to be there.

The question is, what did the jeweler do to the cross before returning it to the lady?