adjusting prongs, shape on an antique platinum setting

[cappuccinocurls]

First time poster! I didn't see a similar post so hopefully I can get clarity here. We found a 1920s platinum setting for a good price. The center stone is .22ct but I have a half carat mine cut I inherited. Will adjusting the size of the prongs to accommodate the bigger diamond be a huge deal breaker? Is that an easy fix? It also looks like the current diamond may be a bit more oval shaped, but my diamond is a regular shaped round stone.

Any advice on if we are getting in over our heads? Will we also expect to pay out the nose for this?

A second question too - there is also a white gold ring that is similar pricing and already set for a half carat stone. I believe it is also from the 1920s. If I have a sensitivity to nickel should this worry me? I assume older rings were not dipped in rhodium like modern rings are?

Thanks in advance!

 

[tyty333]

Most people would not attempt to put a .5 in a .22 settings. In general settings cant be adjusted
that much but...specifically you would need to post a picture of the setting so we have more
information.

 

[chrono]

It will depend on the measurements of your stone. Some old cut stones are quite deep and face up small, so it might fit...or it might not. I've put in much bigger stones into a small setting but it is expensive to rework this and sometimes the modification cost exceeds the setting itself so this should be a huge consideration. There is also the risk of the end result being a bit odd or wonky if the bench isn't experienced with antique settings.

I do not know the alloy used for a 1920 era white gold ring.