From Stitch 'N Bitch Crochet: The Happy Hooker:

I have always liked having a little jacket to wear over a long dress or a low halter (that you may not be comfortable wearing by itself), or that too-skimpy tank, which is why I designed this lacy bolero. It can give that little touch of class to a plain strapless number while also hiding a multitude of sins. Or, wear it more casually, to add some romance to a simple outfit of T-shirt and jeans. It’s done here in a luxurious, silky cotton, but could just as easily be made in a glittery yarn for extra bling. Crocheted in one piece form the shoulders down, there is no seaming anywhere--the sleeves are worked right onto the piece so when you’re done, you’re done! I designed it using the relief shell stitch, which is one of my favorite stitches. It combines elements of the shell stitch with crocheting around the posts of previous stitches, yielding a wonderful textured-yet-lacy look that can’t be beat.And while it may seem complicated at first, I promise that, after a few repeats, you’ll be able to make the stitch with barely a glance at the chart.

Note on gauge: 16 sc = 4 inches. One pattern repeat = 4.5 inches. 8 rows in pattern = 4 inches

For some notes on the pattern from the designer, see her blog post here.