160225 was a very odd plate number I came across on a Jem.Most that I'm aware of are what I call 250k plates [25****] and current 2003' FP15th's have 260K plates [26****] meaning there have been over 10,000 Jem's made since they deviated from the serial plate numbering.Where things go astray is when the Jem line went to AANJ in 93'.This is where you start seeing consecutive numbered plates on the remaining regular joint models that no longer indicate year.9=October, .=November, X=December) 4th and 5th character is the day of production (01 to 31) Although guitars already had serials from 1975, between 19 they used a 6 character serial on pickups: 1st character is a production code (1,2,3, etc., maybe related to different production location) 2nd character indicates the year of production (7=1977, 0=1980, 1=1981, etc.) 3rd and 4th character indicates the month of production (01=January, ...12=December) 5th and 6th character is the day of production (01 to 31) , This old style serial number will either be on the neck plate or impressed into the back of the headstock.Ibanez did not put serial numbers on their guitars. The only way to date these guitars is to find out what years they were available and then comparing all the minute details like scripts, contours, and inlay variances that only the hardcore vintage gurus know.
Some models will never be found in the catalogs, that's just the way it is.Post 11/2011 they changed to alpha, 4 numbers, alpha, the first letter being the month, A for January, the last being the year, B for 2011, C for 2012, etc. - The Guitar Dater Project will decode W, S, I and who knows what other prefixes [factory codes].I do not know how accurate the system is but the few I've run have worked just fine. Plate serial numbers have nothing to do with headstock serial numbers.- Cort serial numbers are denoted with a C prefix followed by either 7 or 8 digits.I'm not sure what year the changeover occurred but using the formula it will be easy for you to tell.