I think the necklace is the perfect opportunity to talk.
(and it's a really sweet thing that he gave it to you \:\) )

it gives you an opening that is a less confrontational thing.
So, tonight, you can start things off by wearing it... and then sitting in his lap. (optionally... make sure the kids are in bed, and wear not much else ;\) )

Talk about how much it means to you that he thought of you like that.. show him how much it means to you.
Then, let him know that you need him to show you that you are "the best wife ever", by his actions and time spent towards you, not just gifts.

If you are understanding, but FIRM (as in, GRANITE-ROCK I WILL NOT be distracted/sidetracked from this)... then I think you have a very good chance at maybe getting him to listen without it being a knock-down drag-out fight.

hope so.

My current status: june 2006. Wife ran out and filed D.
Finalized Jan 11, 2010, after 12.5 years M.
3 wonderful sons caught in the middle