Vintage Siam Sawako Button Up Shirt

So pretty! I could not find anything about this maker but this shirt is beautifully made. -Slightly puff sleeves -Mockneck 🌟 Material: No fabric tag. Most likely polyester. A satin-y feel.  🌟 Condition: Good used vintage condition. This has been hand washed twice but there seems to be a bit of stain on the back of neck. Barely noticeable.  🌟 Fit: No size tag. Fits like a M or L. Please see measurements. Measurements: (All measurements are approximate laying flat) Pit to pit: 20"-20.5" Sleeve: 22" Length: 24" Model is 5'4 and a usually a size Small in tops edwardian