There are many threads on platinum, run a search here and read up on what you find. The suitability of platinum vs gold or white gold etc for rings is often debated.
I unfortunately have nothing to contribute but this. A diamond is said to be the hardest stone, and you have heard the whole 'diamonds can cut glass' analogy etc...so the idea is that nothing is harder than a diamond. But diamonds chip and it's not necessarily a rare thing. If you have a hard object, and it strikes something with much force, then that hard object will not necessarily bend as well as say..a softer gold. Instead it will break, chip, fracture, etc. This happens with diamonds sometimes and it makes sense that it may happen with something such as a harder metal as well--I would think anyway.
Anyway..good luck when you take the ring in, let us know how it turns out.