History

Sigma guitars made in Japan from 1970 through 1979 can be distinguished by a headstock logo consisting of the single word 'SIGMA' surmounted with Martins ('sideways M') logo in mother of pearl above it and an inner paper label giving model and serial numbers. Mar 02, 2020 Sigma serial numbers are hard to read, as they have low contrast and very small font size. On my Art primes, the s/n is located on the barrel along the back edge of the manual focus ring and just to the right of the focus-scale window. The numbers have 8 digits.

• The lens I received is a XXmm f/XX lens for my XXXXX brand camera, and has serial number #233XXXX. The lens you received has a serial number which has not been issued by Sigma’s factory in Japan. It appears that the lens you received is a 'Gray Market' lens, and has been tampered with having its serial number changed.
• While it was long believed that the serial numbers of Sigma instruments were of little use in dating the instruments (except on the DR-28N and DR-35N, which were assembled and finished in Nazareth in 1981/’82 using Japanese-made parts and marked “Made in USA”), today there is a basic understanding of how they work, based in part on the.

Initial construction was in Japan by various manufacturers/factories from 1970 through 1983.

The first Sigmas were typically dreadnought acoustics, although Grand Concert Series (GCS) and classical models were also produced from the early 1970s (1971) onward. Dreadnought models DM-5 and DR-7 are the most common early Sigma guitars until the late '70's. D for dreadnought, R for rosewood, M for mahogany and the number denoting the grade of wood, 5, 7, 9, 11, 15.

Construction moved from Japan (1970–83), to Korea (1984-93/94), and finally Taiwan (1993–2007).

In 1980, model designations were added to capitalize on Martin model numbers: the DM-18, DM-19, DR-28, DR-28H, DR-35, DR-41, and DR-45. The DM-5 and DR-7, as well as other early models continued to be built during this time as well.

Headstock Logos

Sigma guitars made in Japan from 1970 through 1983.

Sigma Serial Numbers | Claescaster

The early 70s models (1970 -1975) can be distinguished by a headstock logo consisting of the single word SIGMA surmounted with the Σ symbol (the Greek letter sigma), in mother of pearl. The sigma symbol is often described as a 'sideways M.'

Interestingly, while playing a Sigma guitar the 'sideways M' becomes 'right side up' suggesting 'M' for Martin.

By the mid 1970's (c1976) the headstock logo design changed to utilize a gold 'Martin style' decal stating 'Sigma Guitars' in script with 'Est. 1970' underneath in a smaller block font.

As is tradition in classical instruments, Sigma classical guitars do not have the headstock logo, and one must rely on the inner label for identification.

Labels and Brands

Sigma Guitar Serial Number Lookup

Sigma's made in Japan from 1970 through 1979 used a paper label to identify the model and serial number of the instrument. The earliest examples had a plain black on white inner paper label giving the model and serial numbers. Later one's (c1972 onward) had white labels that had gold lettering with a border, often reddish-brown or purple in color. All other text was printed in black ink, or stamped on in ink by the manufacturer (model and serial numbers.)

From 1980 through 1983, the end of Japanese production, the back center brace is pressure stamped, or 'branded' in a football shape stating Sigma Guitars/Made in Japan/For/C.F. Martin & Co. followed by an ink stamp of the model number, and prefixed by the serial number assigned to the instrument. (e.g. L-R as seen through the sound hole: Serial number, 'Brand,' Model number.)

Early Korean made guitars show this same brand, only Made in Korea in place of Japan

Serial Numbers

Sigma serial numbers do not provide an indicator of the year in which a particular model was built. This may be due to them being built in several Japanese factories at the same time with no coordination in the serial numbering system. However, while some models lasted the entire run from 1970 through 1983, others did not and were only offered for a limited number of years, so that most models' construction dates can be narrowed down to a reasonable range.

For example, serial numbers on the earliest DR-7's start with 4 digit numbers on through 5 digit numbers. One Sigma DR-7 owner stated 'I have an old Sigma DR-7 Guitar....s/n 6860. I bought it new in 1970.' Further, DR-7's with a four digit ink stamped label serial number and a zero fret strongly suggests a very early build date.

Some early 70s Sigma guitar serial numbers started with 7* suggesting the 197* build date (e.g. 75XXXXXX possibly equates to a build year 1975.) It is widely assumed by owners and Sigma historians that this is correct, though C.F. Martin cannot, or will not confirm this.

'Sigma-Martin USA' guitars built in 1981 and 1982 had serial numbers 900,001 to 902,908. These instruments were constructed using preformed and sometimes partially assembled imported parts, built or completed in the C.F. Martin factory in Nazareth, Pa alongside the regular production line

Serial numbers for Sigma guitars built in Korea and Taiwan are perhaps meaningless, though again some seem to indicate the year of manufacture (e.g. 81XXXXXX.) Since we know these instruments were manufactured from 1984 through 2007 in these two countries, it is safe to assume that a serial number beginning with 81XXXXXX was not produced in 1981.

Classical

In 1980 the paper labels were discontinued and the inner back brace was 'branded.' With the move of production to Korea in 1984, paper labels, this time with a fancy border, were reinstated, although some early 1984 models still retained the back center brace stamping.

Sigma identified their dreadnought and grand concert guitars as 'Second Generation' when the headstock design changed to utilize a gold decal stating 'Sigma Guitars' in script with 'Est. 1970' underneath in a smaller block font, in the familiar Martin headstock decal form. This may have been as early as 1976.

re: My own first Sigma, a DM12-5, which I purchased new in mid-1977 (I still have the receipt) had this second gen 'Martin style' decal logo. It being a smaller, local store, the instrument may have been sitting there for a while before I acquired it. While I cannot be absolutely certain of the year it was manufactured, it was certainly by, or prior to 1977.

High end models such as the D-10 Anniversary model have the 'Second Generation' logo inlaid in the headstock using mother of pearl.

Guitars made in Taiwan have a different headstock decal: 'Sigma Guitars' on top with a miniature version of the 'C.F. Martin & Co.' logo underneath. Some of these guitars also had the 'Est 1970' instead of the C.F. Martin & Co.,' but in a slightly different block font (fatter/wider) from the original 2nd gen instruments. The paper labels for model/serial number identification had also changed again, this time with a fancy border and the word 'Sigma' or 'Sigma Guitars' in gold ink.

The issue of whether or not Sigma guitars are solid wood or laminate wood has been a source of controversy and confusion for many years now. This is understandable since the Martin customer service department now responds to individual inquiries stating 'all' Sigma's had laminate back/sides with solid tops, while Sigma catalogs from the early 70s list the back/side wood as solid.

To complicate matters further, in the 70's Sigma produced a line of guitars clearly identified by Martin, at that time, as having laminate backs and sides: model numbers starting with 52S, e.g., 52SDM-5, 52SDR-7 and 52SGCS-7.

The answer to the question 'Are Sigma guitars solid wood or laminate?' is best answered 'That depends on the year and model.' It is safest to assume that the Sigma in your hand is made of laminate sides and back, however it has also been said that some of the earliest Sigma's were made completely of solid woods.

Later first and second generation Sigma guitars were clearly made of laminate wood for the back and sides, with the exception of several Limited Edition models, such as the D-10 Anniversary guitar.

Sigma Lens Serial Number Lookup

Other Sigma instruments included mandolins, banjos, acoustic and electric basses and solid body and hollow body electric guitars. Some solid body electric guitars were made by Tokai Guitars Company, LTD.

After Sigma musical instruments were built in Japan, Korea, and Taiwan, they were sent to Martin & Co. in Nazareth, Pennsylvania to be inspected and adjusted by Martin personnel before going to an authorized retail store for sale to the public. These inspections and adjustments were made in the 'old' Martin building on North St.(c1865,) then known as the Import house.

The DR-28 was manufactured in Japan, Korea and Taiwan while the SDR-28 and the SDR-28H appear to have been manufactured in Korea and Taiwan only, starting in early 1984. The DR-28 was of a solid Spruce top with laminated Rosewood sides and back while the SDR-28 and SDR-28H was made with a solid Spruce top and solid Rosewood sides and back. 'I have to disagree with the statement that the SDR-28 is made of solid rosewood back and sides as I have 2 of these models both made in Korea and neither have solid back and sides, now I may have just bought ones with a fluke involved but I just thought that it should be noted here!! I entered this information once before but someone deleted it! why? I don't know, but I will see how long it last's this time.If sterling Wood can cite his experiences with Sigma guitars the so should I as I have owned 20 plus Sigmas and still own 5 to this day sincerely, Kevin' The DR-28 and SDR-28 and SDR-28H are clones to the original Martin D-28 and HD-28 guitars and are high quality instruments.

It has been suggested that these SDR branded instruments were the precursor, or pilot program for what has now become C.F. Martins own in-house, less expensive, 'X' series of laminated wood guitars.

Sigma also made a DR-28SC model manufactured in Japan and an SDR-28SC model made in Korea. SC stands for (Sunburst Color)

Sigma Guitars Serial Number Lookup

In 2011 the German company 'AMI Musical Instruments GmbH' launched the Sigma Name/Guitars again. These guitars are all currently being produced in China. There is little known about these instruments at this time.