This Diamond Ring - S5.E19

When Dharma discovers that her drivers license has expired, Greg demands that she be a little more responsible—which is when Dharma discovers she has lost the priceless family heirloom diamong ring Kitty gave her. She discovers it on the roof, coated with tar; and when she takes it to a jeweler for cleaning, she learns it is, in fact, just a really good fake, leading to a confrontation with Kitty. Meanwhile, Pete turns to Dharma for help in getting Gretchen to go out with him. Her simple, sound advice works... Soon Gretchen is head-over-heels for Pete—and he can't stand it. Also, we see Marlene as a judgmental book clerk, and learn that Greg has finally fired her.