Full composition - open-knit (crochet)  - 

Intricately covered by pearly beads in an intricate fashion - please see close-ups

Finished by a single row beads - sleeves, sides, hem and neck line.

There is no closure, but you can thread a few beads through an open knit, this securing both sides at the top (please see close-ups).

Of course, a brooch or a pin would also create a unique closure.

The sleeves run longer - so they can be 'scrunched up'  - this is the intended styling.

This is a beautiful RTW to enhance a simple shell or a dress - it has just enough of sparkle to be classy, elegant and extremely dressy.

There is no fabric/size label - I would assess the composition to be a blend of cotton/viscose/poly/silk.

As for the sizing - as this is an open-front ,  it will cover a wide spectrum of sizes.

This piece is vintage, purchased at a private Vivienne Tam showroom, never worn.

The 1st picture depicts a few of similar styles from Vivienne's Runway.