A common practice for someone who wants a fake diamond, especially a cubic zirconia engagement ring, is to get a high quality cubic zirconia but have it set into a more expensive setting purchased at a jewelery store.
Just because cubic zirconia stones are inexpensive doesn’t mean that the entire piece of jewelry has to look cheap. Sometimes you will find a low quality CZ mounted in a cheap-looking setting and being sold for $20. Obviously this is not going to be acceptable as an engagement ring for most couples.
If you are interested in a high quality CZ, the best method is to order an individual stone from a quality CZ dealer (hint: it’s not going to be found at your local discount store). High quality loose cubic zirconia stones can usually be had for under $20 and almost always under $100 (for just the stone).
Visit classy jewelery stores and look at diamond engagement rings and find a ring style and setting that you like. You can purchase just the ring and setting without the diamond, and arrange to have your quality CZ that you ordered somewhere else set into the exact type of setting that you like.
If you go this route, however, make sure you tell the jeweler that you will be having a CZ set into the ring rather than a diamond. The process for setting a CZ is a little different from a diamond, some different tools are used, and using the tools meant for a diamond could damage the CZ. Some people do this, but they don’t tell the jeweler because they don’t want him to know that he’s setting a fake diamond. If your jeweler makes you feel uncomfortable when you tell him that you’re using a fake diamond, or tries to pressure you into buying a real diamond, you need to find another jeweler.
One of the things that makes CZs obvious is when they are set in a low quality setting. If you get a high quality CZ and have it set into a nice setting from a jewelery store, anyone who sees it will assume it is a real diamond (unless they examine it with laboratory tools, which normal people do not have).