Kan 'n ring steeds regte goud wees, selfs al is daar geen merke nie?
Ja, it is possible. It may pre-date marking, it may have been carelessly sized and the marking cut out, the marking can wear off, there are any number of reasons for there being no marking. The only way to know for sure is to have it tested. If it is real, you could have it marked, or obtain a certificate of authenticity from a qualified expert so this doesn’t come up again. And also so you have proof that it is real. Sterkte!
What is the difference between a titanium steel plated platinum ring and a 925 sterling silver plated platinum ring?
Both are probably fictitious. Who would put a titanium plating over platinum, or sterling silver plating over platinum? You put the precious metal plating over the inferior metal.
Should I wear a gold ring with an amethyst stone?
Normally one should wear amathyst in silver for astrological purpose. If you are wearing it in general you may wear it in gold.