I'm hoping someone can help me get some information about a Sigma SDR-28 I bought my son second-hand a couple of years ago, serial number 89098551. It is in beautiful condition and came with the original hard plush-lined case. He was just starting to play at the time, and since then has gotten lots of compliments from experienced players on the sound and quality. I'd love to have more information about the guitar. (Not that he wants to sell; he's quite happy with it.)

Following internet links, I gather we lucked out. It sounds from the SDR, that it has a solid spruce top, but I am not sure if it has mahogany or rosewood sides and back, and suspect those are laminated. I also suspect it was made in Korea, from other internet chat, but am just guessing. Can anyone guide me to a Sigma serial number site, help me get additional information, and get a sense of what it's worth?

Enjoying the Sigma info. Thanks in advance.