I like that blazer, its very nice. Very dressy and makes you think of psychedelic pop or rock acts from 1968 to 1973 without actually looking like a period piece.
The necklace is great, goes well with the blazer.
I think jeans would work very well with that blazer, if they where the right kind. I don't think the ones you wear in the picture is really working with the blazer. It becomes obvious when you look at the close up of the blazer that the blazer would need a pair of very dressy jeans.
I would go for dark grey jeans (color: anthracite) and a slim fit. Look at
Nudie Jeans Co. / Fit Guide the Tight Long John, Grim Tim or maybe High Kai for the type of fit I think would work with a blazer like that. And they shouldn't look to worn.
Also try with just a shirt and ALL buttons buttoned in the shirt or with only a T-shirt and necklace.
/Flow