Kay was a popular guitar manufacturer during the 1950s through to the late 1960s. It mass produced mostly inexpensive beginner's instruments, many of which were sold under store brand names such as Sears. After 1968, Kay guitars were manufactured under an Asian import company. Unlike other guitar manufacturers, Kay rarely placed a serial number inside its instruments, so to determine the age of a guitar a visual inspection of a model's specific characteristics must be made and checked against photographs of vintage instruments. Submitting your own photographs of the guitar to a professional appraiser is also a way to determine age and value of the instrument.
Inspect your Kay guitar. Make a list of its features. Begin with whether it is an electric, acoustic or hollow body and its color. Note the body type and whether it has a single or double cutaway. Examine the pickups, their number and type (single coil, humbucker). Does the guitar have F-holes or a pickguard? Examine the shape of the headstock and the type of tuners.
Use online resources such as Harmony Central or KingofKays.com. On KingofKays.com, scroll down through the photographs and compare your instrument. Read the specific information about each guitar listed under each set of photographs. For example: "The second guitar is a Magnatone Zephyr X-5. The guitar was designed by Paul Barth, a co-founder of Rickenbacker and was likely made in 1965 or 1966."
Use online resources such as The Vintage Guitar Info Guy website. Scroll down for specific details about vintage Kay guitar models. For example: "The most collectable Kays are any model with the "Kelvinator" plastic headstock overlay with art deco patterns. Used from 1957 to 1960, this headstock was named after the brand of refrigerator that looked quite similar." Compare your instrument to each photograph and look for similarities.
Use a book such as "50's cool : Kay Guitars" by Jay Scott to cross reference the features of your instrument to those pictured. Many obscure Kay models are listed with photographs and dates they were built. You may also wish to use the industry standard "Blue Book Of Electric Guitars" by S.P. Fiestad to determine the value of your Kay once you have identified it from a photograph.
Use a paid professional guitar appraisal service such as Vintage Guitar Pro. Take five photographs of your guitar as indicated on the "appraisal" page on the Vintage Guitar Pro website. Ensure you photograph the guitar in a well-lit room and that the closeup headstock photographs are clear and in focus. Click on the "Attach photos link," upload your five photos and click "Purchase Appraisal." You will receive a written evaluation with the guitar's age and value.
Kay manufactured guitars under several different brand names depending on the store that was selling them and the year they were manufactured, so they may be listed under names such as Sears.
Appraisers charge a fee for their services.