I have candle sticks for Jewish Sabbath celebration from my Grandmother. Not the same as wearing jewelry, but they are a mixed memory for me. I loved my Grandmother, but the religious use makes me uncomfortable.m
To me it's all about being honest with myself. I try to behave with honor and respect to myself. That's what I believe my Grandmother would want for me.
The candlesticks are where I can find them if I want to.

Rings can be resized and if my grandmother had left me across I would wear it. If my Uncle dick have left me jewelry I would have pawned it. In fact I need to get out the Silver Service he gave me as a wedding present and figure out where to sell it. Partially because he was a dick and mostly because no one needs a silver service unless they have a butler.

What a well written description of the dilemma.. From that alone, I’d trust your judgement ~

Do what makes YOU happy

Keep it so you can remember and if anyone asks why you are wearing it make it plain as to where it came from. That should do it.

As for the cross, it irks me to see people wearing them because they assume Jesus would be OK with a cross. How would that be? I'm waiting for a nice chain necklace with an electric chair on it. Then I could tell those that confronted me for wearing it that I am more modern than they are. I have a work colleague who hears this and suddenly claims he never makes fun of anyone's religion.

It’s your grandmothers. She probably wore it with pride. She left it to you for whatever reason. I think you need to realise it’s not about you! It’s about her and it’s seems you are thinking that others won’t approve. Why on earth do think anyone would give a rat’s arse what you wear. What message do you think it sends out and whose business is it anyway? It’s weird that you have a problem with not respecting your grandmother’s bequest if you want to wear it!

I like the idea of adding on to the cross or star to make it something of your own. Nice to have a foundation of your grandmother's religion, but let it morph into something you believe in more fully now, or something iconic to your current life. Maybe a jewelry designer could help you out with an idea. I love the idea of feeling the embrace of your grandmother, by her jewelry, but it should also be on your terms.

I have a lot of my mother's and grandmother's jewelry and special pins, including a "Nixon's the one" pin. The jewelry box is where a lot of the stuff will stay, haha!

Absolutely not you honor them not the religion

I have a coptic cross from my godmother.
I feel the same way about my cross as you.
Maybe you could put a petite icon with it on the chain, like an atheist symbol, a satanic symbol, or a Micky Mouse? That way, it might not feel ostentatious.