I can't see that many options with that color - if they were relatively new, I would have said 'freshwater'. Old... I'd guess they are costume jewelry as well, not real pearls.
Perhaps there are other options for a strand of well matched, round, 5mm golden pearls, but the options I can think of are very exotic, quite valuable, rare and altogether terribly unlikely.
Now, please take into account that I'm no expert and all the data I have about the pearls is approximate age, shape and size and a guesstimate of yellowish 'golden' color. I really doubt that any professional jewelry appraisal would give a professional opinion based on this little. One can always guess though.
My 2c