I tend to use fountain pens for work - don't know why but I do - and colour wise blue or black ink tends to be the norm although one pen is filled with turquoise quink - the price £2.39 for the bottle which shows how old it is - but struggled to find a new bottle - Now I find not only can you turquoise you can get green, red, pink & purple to boot - need to find if it is in bottles or cartridges or even if you can get it ........I bet it ain't £2.39 a bottle now