On Sunday's episode of Keeping Up With the Kardashians, Khloe freaks out because she can't find her 12.5-carat radiant-cut engagement ring.

"I'm going to die!" she screams to her mom Kris (see video, above).

As she rifles through her jewelry box, her older sis Kim tries to calm her down.

"It's got to be here somewhere!" Kim, 29, reassures her.

Khloe, 26, is afraid to tell her husband Lamar Odom because he is already stressed out because it is playoff seasons.

Says Khloe (who celebrates her one-year wedding anniversary this month): "I do not want to upset Lamar at a time like this."

Watch the full episode of E!'s Keeping Up With the Kardashians Sunday at 10 p.m. (EST) on E!