Is it possible to make out the age of diana rifle/pistols using serial number.
does anyone here knows more on translating serial numbers.

I don't know about the older models but mine are marked on the left side of the reciever towards the rear with numbers such as 12 04 meaning December 2004.The numbers are small.
Gary

Pre-war Dianas very often have the month/year of manufacture stamped on the cocking link, stock, or other locations. Postwar guns began date stamps on the left rear receiver in the early 1960's, and you will see this on the great majority of used Dianas found today.

There was also a period in the 60's and 70's when Diana put the last two digits of the year of manufacture in front of the serial number, giving a 7 or 8-digit number.

There were also periods where no date was stamped and for these I am not aware of how to correlate the serial with the manufacture date.

Here's a great example of a Diana 27 that shows the date stamp on the rear receiver. "01 70" means January 1970 of course. Note it also has "70" as the first two digits of the serial number, as I described above.

The practice of "prefixing" the serial number seems to have lasted only a few years, but you still see the date stamp on Dianas being made today.