@littlekay111: I agree with the others who say ‘trust your eyes’ and that you don’t wear the certification, but only up to a certain point. The average consumer hasn’t seen an ideal cut diamond before, so they don’t know if the ones they are being shown are the best cut they can get. There’s where a reliable certification comes in handy (I recommend only considering AGS/GIA certified diamonds), they provide a standard to base your decision on.
If you want something to think about (and have some time), watch this video in HD to see how super-ideal cut diamonds are supposed to look. He compares stones of different cut GIA cut qualities. It’s even more interesting if you listen to it with the sound off at first. Many people will think the first two diamonds he shows are pretty sparkly and well cut, even though in reality its a low cut quality.
Some tips I can think of…
1) If buying uncertified or certified from a lab like EGL/IGI/etc, ask the jeweler to provide an ideal cut GIA/AGS stone as a benchmark (a Hearts on Fire diamond can work too, they are generally very well cut – but with a premium price). An ideal cut rating from the other labs like EGL/IGI can mean anything.
2) You’ll notice some EGL certifications specifically say the diamond is certified conflict free. Many jewelers are baffled by this, since unless an EGL employee follows that specific diamond through the mining/cutting process personally, there’s no real way to guarantee it is conflict free. Don’t let this sway your decision into buying one, it doesn’t mean anything.
3) If graded by GIA/AGS, most VS2, many SI1, and few SI2 stones are eye clean.
4) Depending on your color sensitivity, an H color diamond is plenty white. It’s generally recommended on staying between 2 color grades of your side stone color.
5) A GIA Very Good cut isn’t very good at all, don’t be fooled by the wording. See the video above for proof.
6) Jewelers consider fluorescence a bad thing, and they’ll tell you it causes stones to appear milky. A GIA study concluded that a negative effect only appeared in 0.2% of the fluorescent diamonds they received. It actually helps the diamond appear whiter in light that has UV, like direct sunlight. Read about it here
7) Just because a stone is a ‘hearts and arrows’ diamond, doesn’t automatically make it the best diamond. There’s no standard to what is called a hearts and arrows diamond.
8) Like PPs have said, do not compromise on cut. Period. If the jeweler brings out a stone, it’s the first thing you should ask for. A ideal cut I SI1 will beat out a Very Good cut D IF diamond each and every time.
9) Be careful, do your research, but don’t forget to enjoy yourself! The process is a great experience to go through, and you’re lucky to be doing it with your FI (many girls don’t have that chance!)