Should I let him have the ring?

I agree with others here, 25 is not too young a lot of us were married with children by then.
I think the idea of lending/ giving your son the money to buy her a new ring is sensible, the heirloom ring could be offered at a later date for the first wedding anniversary for example.
Give the girl a chance she is probably quite nervous at meeting her prospective new family.

joopster you sound determined to become the mother in law from hell.

You could mention to your son that you think his future wife deserves her own choice of ring.
As lemongrove said, they may have a daughter of their own one day and you may want to pass it on to your DGD.

Leaving aside the issue of the ring, I think you need to rethink this and try and get to know the girl a bit better. My first DiL came across like that when I first met her, and, we never had what you would call a warm relationship. It was just the way she was. But she was so very good for my son - a warm and loving wife with his best interests always at heart. I wish she was still here.

Even if you don't warm to her, you have to accept your son's choice of partner and welcome her to the family. You don't want a family estrangement.
Why not suggest to your son that he asks his girlfriend if she wants his grandmother's ring or she would rather have something new. The odds are that she will want something new but, if she wants the ring, I think you have to accept it as it's been discussed in the family for a long time.

25 is not too young, my family was complete by then. Can't imagine a young woman wanting a granny's ring, just keep it.

I've got my grandmother's ring which I treasure and I wouldn't give it to anyone. It is in my Will to go to my eldest daughter (which was how I got it) and failing that to the next and the next. After that it will go to any female of grandmother's blood, preferably a granddaughter of mine.

The ring is a different issue to the feelings for your prospective daughter in law. Give your relationship time to develop.

You can't possibly know her after such a short time.Aloof could be shyness as others have said.
Still I think you should keep your mother's ring, after all she left it to you and that makes it priceless.

Help your son out with a ring bought by him for his girlsfriend. If he can't afford a ring at 25 then he should consider if he can get married. And if that is the case then its better the girl knows it.

And your ring remains in the family where it belongs.

I always thought it was seriously weird that Prince William gave Kate his mother's engagement ring after all the hurt and destruction in that marriage. I would have run a mile! I think DS should go out and buy a shiny new ring, although it seems the one in question means something to him. I think you need to have a long look at yourself and your attitude to his GF. 25 is NOT too young to be engaged and it doesn't sound as if you have been exactly effusive in your welcome to her. Apron strings have to be cut eventually whether we like it or not!

I was a very shy 19year old when I met my future mother in law. We were 20 and 21 when we married. I'm sure she was worried but she was always warm and welcoming and I still miss her. What a shame to have taken against your future daughter in law after only three meetings.
Incidentally I am still quite restrained when I meet people, but I'm worth it once I warm up a bit - I hope

I don't think that she'd want a ring from your family. As others have said she's more likely to want something more modern and brand new. Perhaps your lad hasn't thought it all through, what with the excitement of proposing and the thought of using your family ring. I think a quiet mother/son word is required here. As for the future DIL, I hope in time you'll grow to like her more. My son's partner of 4 years (my future DIL) is a very difficult young woman who makes it clear that she tolerates me only, despite my standing back and never inerferring. Still, she is his choice and they are happy which is a good thing.

Our DS didn’t have two beans when he proposed to DiL and could only afford a white gold band with tiny specks of diamonds in. Very pretty nontheless. I did have a garnet and diamond ring from my MiL which would have done, but it wouldn’t have been fair on my other two children to have given it. DD1 has a small simple one and DD2 doesn’t have one at all. DiL was a bit miffed that her ring in no way compared to the ones her sisters had. But now she sees it as something really special. Something he’d given as much as he could afford for. One day she will have the garnet ring. And other jewelry. But not yet. (I’m not dead yet.) I think he should buy his own ring for her.

You've always said that you would give your son the ring for his fiancee, so of course you should honour that. If she doesn't want it (and I don't think she will) then you're off the hook. The bottom line is, of course, don't make promises you can't keep.

Just say you don't want to part with your mother's ring. Start wearing it. Leave the happy couple to sort themselves out and solve their own problems

I wouldn't give it to them. It belongs to you for as long as you wish to hold on to it.

I agree with people that are saying that 25 is not young. He has been an adult for 7 years.
I also agree that shyness can come across as aloof and of course she will be shy if she is meeting her boyfriend's mother. It suggests that she cares about him and what his parents think.
As there has already been comments made about him having the ring, I think refusing to let him have it might lead to a fall out. You could suggest that he makes sure that she really wants an older family ring as an engagement ring but I would let him have it and think of it as a gift to him. It is your choice though and if you are going to feel resentful you have to weigh the various feelings up.

“ I can't bear the thought of this young woman wearing it.“

And I thought she was the one with the problem.

...you need to engage your son in getting to know her.

Resolve this loathing and you may be more inclined to search for that ring.

Then, perhaps, all three of you could join the search while sharing memories along the way.

The ring should be the subject of a wider discussion, including your potential daughter-in-law, and you should bring your mum into it, with photos of her, and some reminiscences so it's clear to all concerned that this is a family heirloom of great sentimental value. You can jokingly say that its wearer is the lucky custodian of the ring until it's time to be passed on to the next generation. If you are up front about this, the girlfriend has the opportunity to retreat from or embrace these sentiments and your son is in do doubt about how you feel. This is actually your memory of your mum, and the new girlfriend doesn't trump that.

No I wouldn’t give the ring away, if your not sure and it’s if great sentimental value to you hang on and see.
May be she’s a bit nervous of you all get to know her more if you can and as you said she might want to have her own ring.

I agree with Grannyticktock. Just be honest with him...perhaps not about your reservations (!) but about the ring and yes he should be able to afford a new one if he's proposing.
Start how you mean to go on...if he DOES marry her it'll make it easier for you all in case something comes out inadvertently in a future disagreement along the lines of "...and I never wanted you to have that ring!" Ye God's what a thought.
At least he wants to marry the lass....so many don't bother these days. Good luck my dear.
Other option....have it reset as a brooch or pendant for you.

I am always a bit surprised when i hear that someone in their twenties is settling down. Yes years ago we all got married very young, we mostly hadnt had extra years at university and had started work at 15 or 16. It wasnt unusual to marry at 19 or 20. I was just 21. When i had my first daughter at 26 i had ‘old mother’ in capitals in latin ( prima gravida or something) on the front of my hospital file.
It is different now and many you ng people i know are still unattached ( or unwilling to Commit) into their mid thirties.
I understand why the op is a bit concerned. And no, i wouldn't give up the ring just now, but would certainly try to get to know the young woman better if she is the one her son has chosen.

My son was 22 and his wife 21 when they got married. I gave my son his grandmother’s ring and his wife loves it and wears it everyday. I’m surprised that you think 25 is too young. My son is now 40 and they are so happily married with one son who is doing his A levels. With regard to him only knowing her for eight months, my daughter met and married her husband within six months and they have just celebrated their 17th wedding anniversary. It’s his life. Yes, he may be making a mistake, but it’s his choice and he’s a grown man. The ring is another issue. She will probably want to choose her own, but she may treasure the family heirloom as my DIL does, you obviously don’t really know her enough yet to judge.

Why don't you invite them both to tea, show her the ring and ask if she would like it to be her engagement ring or if she would prefer something more modern? If she says she would like the ring then I think you ought to let your son have it but I have a distinct feeling she would prefer a new one of their choosing but may not want to say so in case it offends you. You can always offer to keep it safe until they have children to hand it on to. I don't think 25 is too young to get engaged at all - you don't say when they will marry so it could be several years down the line. I am biased though - I was 19 and my late husband was 23 when we got married.

This young woman may well be in your life for the rest of it so I would welcome her into the family with open arms. It may work out, it may not but only time will tell. At the end of the day it is just a ring, surely relationships are the most important thing? There are no guarantees in life but it would be silly to cast a cloud over things at this early stage.

This really resonates with me. My brother was married for 12 years. During that time my mother gave his wife a lot of family jewelery, including my great gran's wedding ring. Well they split up and she went back to her home country. She kept all the jewelery which I think was morally wrong. If you give this girl the ring you may not get it back if things don't work out.