Question

add a question tag to sentence - this is an expensive not necklace

Answer 1

 This is an expensive not necklace
 ANSWER IS 
                                      
                                  This is an expensive not necklace   ISN'T IT

Answer 2

Given sentence:

This is not an expensive necklace.

Sentence after adding appropriate question tag:

This is not an expensive necklace, is it?

Additional information:

Question tag may be simply and compactly defined as a single phrase or group of words that is added at the end of a statement or sentence in order to and converts it to a question.

The British English call it "Question Tag" whereas on the other hand American English call it "Tag Question" or "Tail Question".

Question tags are generally common in familiar conversation and not in formal writing or conversation.