Need an adjective for "money"?

[live2learn1994]

Complete the sentence:
The diamond ring she wore cost a _________ $10 million dollars

I remember reading similar sentences. The blank contains an adjective with an -ing ending ( as in "booming"). Please help me guess the word.

 

[Lila]

Astounding
Waping

 

[ArTiSt~N~PoEt]

Whopping