This is a gorgeous shirt from Nat Nast Luxury Originals.

Made of a blend of silk and cotton, it's dark blue and features white squiggles.

The shirt has a left chest pocket, a slim fit, and a square tail with side vents.

This shirt is in absolutely MINT condition and has been recently dry cleaned.  Guaranteed to be authentic and perfect. 

Marked L.

Across the back, laid flat and unstretched, the shirt measures 23 inches from armpit seam to armpit seam and 29 inches from the collar seam to the bottom of the back.

Please check/know your measurements before buying as tag sizes differ between brands and even within the same brand.