The blanks in the flat below can be filled in with either of two words. The two words differ by only a single letter (the fourth). The meaning of  the flat's sentiment completely changes, depending on which word is used.

You gave to me a zircon ring
When riches we had none.
You now give me a diamond.
I prefer the _ _ _ _ _ _ _ _ one.

Answers:

PRECIOUS  / PREVIOUS 

Credit:
The Enigma
NPL Magazine
September, 2019
LEXMAN