A completely mediocre product. I was expecting a lovely glossy, easy to apply polish - but this is runny and gloopy at the same time. You will need at least two coats to get a good coverage. I will not comment on lasting power as this can be affected by your base & top coat. I use it on my swatch sticks (for duochromes) so that it is not a waste and will not be buying another one when (and if) it does run out. Also the price is high for me (in New Zealand dollars) when I can get a Jordana polish that is better for much less. continued >>

Went on opaque in one coat for me but I wore 2 coats over my usual base coat. Black Onyx is an opaque, black creme polish with a lovely shiny finish. If I wasn't worried about chips, I'd probably skip a top coat. Unfortunately you will probably need one as I found that it chips very easily. I got chips after 3 days which I found a little unusual for an OPI colour. I'd probably get Rimmel's Black Cab next time. It has the same effect and consistency, it's a lot cheaper and it last a lot longer. Great for layering glittery polish over but I wouldn't buy it again.

Best black polish ever. It's a gorgeous black and looks so glossy and classic with a shiney top coat.

I never really thought black would look good on me. Not really sure why I thought that. Anyway, this black does. It's like a nice, creamy jet black. Very shiny. Doesn't make my nails look dull or dead.
I think two coats of polish and the application was smooth sailing.

This is a pretty basic colour, and it is very very pigmented black. On its own with two coats it looks amazing, although a little bit too black for everyday wear to the office (depending on where you work). The formula isn't streaky, it it goes on really smooth. Depending on how well you put on nail polish, it's obviously very unforgiving if you smudge on your cuticles, so I usually paint on one hand at a time.

I love using this colour as a base, and applying a top glittery colour. The black base really brings out the shimmer of any polish. For example, OPI's 2009 holiday shade Merry Midnight is a bit sheer on its own. Applying one coat of Black Onyx and Merry Midnight on the top, really REALLY highlights the amazing glitter that's in the polish. Using it as a black base really amplifies glitter/shimmer polishes. I've replaced this colour a few times, and I will continue to replace in the future.

OPI's nail colors are amazing quality. This is way better than Chanel's black satin, which can easily get scuffed up. Lasts an entire week with no top coat. only thing is you must apply 2 coats else its watery black instead of true black.

Love this Black!! easy application, brilliant shine, and completely opaque with two coats. I usually wear this colour on my toes and I get so many compliments on how shiny it is. I will certainly repurchase this when I run out.

I am in love with OPI nail polishes this black one is awsome it had great shine and it lasts!! ♥ OPI continued >>

This is ok but nothing special.

The first coat goes on too sheer for a black polish and you couldn't just do one coat. Two the minimum you need to get a deep black colour, but then when it's too thick, it looks gluggy and chips easily.

Compared to my other black polishes, it also has a tinge of like dark dark brown through it in certain lighting.

I've bought it twice and both of the bottles became a thick mess after using not even half the contents.

Creamy, opaque, true black; dries to a shiny finish. You'll need at least 2 coats (or 3 really thin ones) to achieve the colour of the bottle -- so don't despair when your first coat results in transparent charcoal, it does build to a true rich black. Glides on without streaks; lasts for days without budging. I won't repurchase because it's just too much; it'll look fine for a night out dancing but for everyday it's just too...well, black. But if that's what you're looking for then this is your shade.