Go with white sapphire, which could be natural (was mined from the earth), or synthetic (is still a real sapphire, but was grown in a lab). CZ isn't good for a ring you will wear everyday. It scratches and chips very easily because of how soft it is, plus lower quality cz can discolor to a unpleasant yellow-ish shade after years of wear (not all cz will discolor, but some will). Sapphire is the next hardest commercially available stone next to diamond. It will last you a lifetime, and while it will pick up some knicks over years of wear, a sapphire can always be re-polished 20 years down the road and look good as new, a cz will have been long gone. Nothing that isn't a diamond will ever look like a diamond, because every gem material has different properties and ways it reacts with light (which is why they "sparkle". But a white sapphire has a beautiful look of it's own (they don't cut natural sapphires the same way as a diamond, but they do cut synthetic sapphires with a brilliant cut sometimes). If a natural one is in your budget (they actually aren't very expensive at all, because blue, pink and yellow are "desirable" colors in sapphire, while white is often overlooked, therefore has a lower price tag due to lower demand), then go fo that. The mix-cut they use on them (assuming your looking at a round) gives them a beautiful, almost vintage look.
I work in a jewelry store
Edit: in regards to what the lady above says, if you wear your ring and put on lotion, wash your hair, wash the dishes, work in the garden ect... it will get dirty, doesn't matter what stone is in it. Windex (not dish soap or anything else, which will leave residue) and a soft toothbrush does a great job for at home cleaning, without doing any damage. You should also take it in every 6 months to have it checked and professionally cleaned at the jeweler you bough it from.