This is the most striking blue eyeliner I've ever owned; at that level of color, I was surprised at how wearable and long-wearing it is.
Sapphire Strength is a very accurate kenning for this color. It's a deep cerulean, and its intensity is buildable to the point of satin-esque, deeply opaque blue. This color really adds depth and definition to my brown eyes, and I have not had problems with it fading. In order to get the color flowing, you need to have a heavier hand when applying this liner; you need to go over your lashline a few times in order to see its potential. I suggest warming it up a bit, since it doesn't draw well if it's cold. However, the resulting color is well-worth it, and looks simply stunning. Love.
This eyeliner is not as smooth as some; like aforementioned, you may need a bit of arm power to really achieve the best effect. It's not waxy per se', but it's not creamy, either. However, I don't really mind.
Now, its staying power is incredible. I think someone below might have said how this product has 24 hour wear, and that is accurate to a t. Even though my outer corners tend to mess up my lower lash eyeliner, this one stays true for the entire 19 hours or so per day that I have makeup on. (I use primer underneath.) It doesn't need touchups at all, either. Its staying power is pretty much what I'd consider ideal.
The one thing that is a downer is the packaging. Idk if it's just mine that does this, but you really need to twist and to twist in order to get it out of the tube, and it won't twist back down. In fact, I'm having problems right now, since the eyeliner needs to be twisted out a bit more, but it does not want to cooperate. I'm worried that I'll have to repurchase this liner- I might not even be able to get full use out of it.
Its price is at about the median of drugstore eyeliners, like $8, which is a reasonable price to pay for such a great product. I highly recommend this liner, but only if you're patient enough to deal with its packaging.