http://www.ebay.com/itm/281337853385
This vintage hunting vest was made by the Gem Shirt Company of Dayton, Ohio in the 1910s. The Gem Shirt Co. was founded c.1888, and diversified into canvas hunting clothes in the early part of the 20th century, innovating the usage of lined waterproof game bags. They were a high end maker at the time, making their products from an excellent grade of cotton canvas duck. They ceased production by the 1920s.
The vest has 37 closed bottomed reinforced corduroy shotgun shell pockets on the front of the vest. The corduroy material is somewhat unusual, a nice early detail. The back is belted, but instead of the usual vest style central belt and buckle arrangement, this one has double side adjuster belts. It has Southwick buckles, a type patented in 1906, also used on some DuxBak vests of the period. It has an early black and yellow label, which identifies this model as the “Special”, made for “Outers and Hunters”. The grouse on the label is carried through onto the figural buttons. They are removable ring-back, of the type common on workwear of the period.

Chest (pit to pit): 22″ (doubled = 44″)
Length (front): 24″
Length (rear): 19″

For another vest made by “The Gem”, see here. A comparison of the two is below.

 

Patent no 819,180, as found on the back of the buckle.  Patented May 1, 1906

The logo for “The Gem” was trademarked in 1911, although it had been in use since 1888. The label on this vest reads “Registered”, dating it after 1911.

Ad for “The Gem” from 1912

The Gem Hunting Coat, 1917

1918. Guiterman Bros Town and Country vest, Gem Hunting Coat and a Springfield Rifle

1923. Gem Hunting Vests and coats.  This is the last I can find on the company.