Graphite 
One of the new colours in the blacks. While I picked up the bottle I must admit I was thinking of a darker black. As I wrote with this ink, the grey-black tones are you see as the ink hits the paper and when it dries.
It may be me, but I kind of see a bit of green in this ink also.
Good performance in a couple of different lines of pens. It dries within a reasonable time frame. I have been using it in OMAS and Pelikan pens with Broad nibs. No shadding in terms of colour. The line of ink seems very consistent on all the strokes.
For those who want to use a grey ink, but want a little more character to the colour, then this is an option to consider.
The colour swatch on the Diamine website makes this ink seem a bit darker in colour than I have found writing with it.
Jet Black
I like this colour. It has good flow and a good dark tone. There is no under colour that comes out, even when writing with a very broad nib. Diamine makes several different blacks. If you are looking for the deepest available form Dianine, this would be your best choice.
In testing this in with various pens it is a very good performing ink.
I gave the ink a water test and I was impressed, the ink held to the paper. There was some smearing, as to be expected, but all of the ink did not just lift off the paper.
I wrote a line of text, waited five seconds, and then dipped my finger into a cup of water and ran the wet finger across the text. Not bad.
Colour swatch from the Diamine Ink web site follows:
Onyx Black
This is another great black ink by Diamine.
It has a very dark colour tone with no undertones of other colours - even when writing with a broad nib where a very heavy line of ink is on the paper.
The ink is smooth flowing and dries relatively fast on the paper. I have tried this ink with various nib widths and it has very good performance.
The ink is not waterproof, but to see how this ink reacts with water I gave it a water test.
After writing, I waited about five seconds, dipped my finger into a cup of water water and then ran the finger across the text. I was impressed. Yes there is smearing, as to be expected, but the ink hung to the paper.
Colour swatch from Diamine Web Site follows:
Quartz Black
This is another tone in the black series from Diamine.
I have found this balck to be dark and rich with only slight undertones of grey..
I have been using this colour for some time and enjoy it very much. It is a good performing ink. The time to dry on the paper is reasonable. My tests indicated that between five and under ten seconds was enough for the ink to dry, and for me, that is writing with a broad nib which leaves a fair amount of ink on the paper.
Colour swatch from Diamine Web Site.
Grey
This grey has good character. I find that I use this colour more for personal notes and cards as opposed to business purposes.
The colour looks very good on cream paper. It has a very distrinctive look.
This is one of the best grey inks that I have used because of tone and colour saturation.
I am using it in broad nib or stub nib pens, and I am a "heavy" writer in terms of the pressure on the nib. The ink flows and takes more than 10 seconds to dry. This is a little longer than some of the other Diamine colours.
Colour swatch from Diamine Web Site is a good representation of the ink colour.