Help with ring markings.

Hi to all,
Got lucky and found a few rings on the local beach yesterday after all the big seas recently. Two gold rings have markings that I am am trying to understand. One has 18ct mark plus 381. Does anyone know what the 381 means.
2nd ring has letters & numbers and maybe the makers mark - (PPJ "mark" 610P). Although gold in colour I am not sure if it is actually gold and what the marks mean. Spent couple of hours looking for answers online but without luck.
Any help would be welcome.
I will attach a couple of photos.

Nice rings NedK :Y:

Sweet finds :Y:

Nice rings
381 looks like a after thought , could be the wedding anniversary 3rd of 81. I know one bloke that done that cause he was hopeless with dates.

Thanks for your input aussief. Maybe something simple like that. You could be right. Can't find that number anywhere relating to gold after a good search.
After posting the photo of the other ring, PPJ "mark" 610P and seeing it on the forum I enlarged the original high resolution photo on the computer. I am thinking that it is only plated with gold.
Cheers

The 18ct ring has been hallmarked by the manufacturer and the 381 is most likely a catalogue number added by a wholesaler, or a stock number by a retail jeweller.

If you Google "610P ring", the alphanumeric is part of a common US jewellery catalogue number and presumably identifies a particular manufacturer, although I haven't been able to find anything in the style of your find. Searching for "PPJ" doesn't seem to lead anywhere either. As it isn't hallmarked, I'd assume that it is gold-plated base metal.

Thanks Grubstake. Pretty sure you are right about the "610" being plated. Your thoughts and looking at an enlarged photo pretty well confirm that. Couldn't have been in the sand too long as it is in great condition.
Learning a lot about jewellery in last 24hrs. Another ring I found at the same time looked like stirling silver but turned out to be "German Stirling" which has no silver in it at all. Lots of imitations out there ands lots more to learn.
Thanks to all.
Cheers