This Sigma guitars ad was published in the UK 1974. It reads:

Sigma Guitars: designed in the States, made in Japan to give the best of both worlds.

Sigma guitars are made to the design and specifications of the world famous Martin organisation of Nazareth, Pa., U.S.A. And they are made in Japan by one of the world's foremost guitar makers who was specially appointed to meet the exacting standards of quality laid down by Martin.

This means with every Sigma you get the economy of production from Japan PLUS the backing and quality of C. F. Martin.

If you’re in the market for a new acoustic guitar, do yourself a favour and get to a Sigma. It’ll get to you.

Six string, twelve string and classic models to choose from. Prices inc. V.A.T. from £45 to £77.

3173 Sigma 6 string 'Jumbo' acoustic. Back and sides are in laminated, dark, matched rosewood with a selected spruce top. Bound in black and white trim with a matching rosette around the sound-hole. Slim neck with slightly cambered fingerboard, 14 frets clear of the body. Pearlex position markers on fingerboard. Bound head with rosewood overlay, individual chrome machine heads. Highly polished lacquer finish.