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.

Black Onyx is a glossy, true black but it has a horribly thick, gloopy texture. Maybe I bought a bad bottle because my other OPI polishes have a thinner consistency and are much easier to apply, which is a shame as this is my favourite and most used colour. It also seems to take longer to dry than the others.

For those who love the black polish trend, this lasts far more than its expensive counterpart that launched the trend (Chanel)....This doesn't chip as easily as the Chanel polish, and the black is a true black. A good solid black that really lasts.

Love this polish! As has been stated, it is a perfect, creamy, true black -- no shimmer, no glitter, non-metallic. The finish is gorgeous and, worn with top coat, I end up removing the polish before it shows any significant signs of wear. By about day 4 I have some barely noticeable tip wear and by day 5 I'm usually ready to see naked nails again, so I've never seen this truly chip. I always use a base coat, so I don't know about staining but I presume that it would. Looks fantastic in the summer with a tan!

OPI Black Onyx is a perfect cream black. It really does look like a black onyx stone on my nails! I highly reccommend a base coat with this...and even after I removed the polish, my nails were kinda 'grey' for a while. But hey - it's black polish...you run the risk! I think this is a very classy black color (no shimmer/glitter), and was found perfectly acceptable at my desk job. I got this for retail price on eBay...only place I could find it.

4 lippies mainly because it chipped fairly quickly, which normally doesn't happen with OPI, but it did with this color. Probably more noticeable b/c, after all, it's freaking black and easy to see chips. But i love it.

I love OPI polishes in general anyway, but I loved this polish because it gave me great, streak-free, opaque coverage in one coat. This polish dried to an extremely glossy, deep black finish. There's no shimmer, just a creamy, long-lasting, chip-free polish.

Black Onyx is a shiny, pure black creme polish. Much like a black onyx stone! :P Two coats were completely opaque, and streak free. It was easy to remove and didn't stain my nails (I did use a ridgefilling basecoat for extra protection). I only wore it for one day though. I didn't get tip wear, but I needed a change.

Love love love. Jet pure black with colour so solid you actually only need 1 coat. The best part is the finish which is high gloss - looks like new car paint! Perfect.

I LURVE this basic black nail polish, I wish they kept this one as part of their basic OPI collection. This is a wonderful basic black, it looks so classy with a glitter topcoat. This reminds me of when I was a teen, I would only wear black polish. Too bad it was Wet And Wild brand so it would chip within an hour of applying it. Anyways, this reminds me of my teenage-dom but better quality in OPI form. I <3 this polish, and I would recommend this to anybody! continued >>