Quite honestly congratulations. My sister is a platinum diamond designer, was one of the top in SA till she got up and quit, and moved abroad to be a farmer. She still makes Jewellery but for really select clients. So I got taught all about diamonds etc.
But in all honesty, if the girl loves you and really loves you, then she couldnt care less if its a cheap steel ring or diamond ring. Sure diamond is just bling but anyway. It's the love that counts. Guess you have a keeper.
Ok next step. You have to deside if prenup or not. SA court lately has been chucking out prenups and out of community faster than people use toiletpaper which is a worrysome sign. I think its targetting a specific religion.
However...
1. In community of Property. Everything you have and hers gets split 50/50, you would also need her permission to take a loan, and with some banking etc. If you do own a business and it goes bankrupt (some sadly do), then she is liable too.
2. Out of Community. What's yours is yours and hers is hers. However a judge can still overrule this and give her half or more. SA Judges lately.
3. Out of Community but with Accrual. So you have to list everything you bring into the marriage ie property, vehicles, investments and pensions, and can list what to exclude. From there on whatever you build up together gets divided into 2 if it ever leads to divorce. However.... you are allowed to apply for loans on your own name, and she wont be liable for this, and if a business goes bankrupt, they will only go after you and not her. Generally this is the way to go.
Now these items are difficult to discuss, but yet divorces do happen, and so does bankruptcies. You can however still with the out options give her access to your accounts etc.
Inheritance is normally not shared with spouses, but you have to invest it specifically otherwise it can fall part of the marriage estate.
Also normally with pensions, the wife is allowed pension interest. This is 15% per annum interest, whether you got this on your pension or not is your own issue. Some does walk away with 100% of their husband's pensions.
Do consider that although marriage is love and all that, its also a financial contract between 2 and more parties. If you ever watched a series like "The Heirs" or "Inheritors" on Netflix. Its pretty spot on how it is in some countries. Its a joining of two families.
Lucky for you she isnt Asian because that can be costly.
Typical engagement of an asian couple. Yip the groom to be has to give a lot of gifts to the bride and her family