If you’re making copies of Roman mosaics or producing contemporary ‘inspired by’ mosaics then you need to start with a basic colour palette. Here is a list of the main colours you need to start with. I’ve included the best stone colours to help you, (when I talk of colours I tend to be refering to the various shades of a colour as with stone it is not that often that you get a ‘pure’ colour except with black or white).
You need Black, White, Red and Yellow. These give you enough to start with for your geometric patterns etc. Next add Dark Red and Green. After this look at your specific piece you want to create and you’ll be looking at adding brown and various shades of red/pink which gives you the range to start on figured and portrait work.
White – Firstly I don’t mean white! The background stone you tend to see in Roman mosaics is an off-white, almost a very light beige colour. Pure white is very rarely used in a Roman mosaic except for small areas. The reason for this is that white as a background produces a very flat effect. Using off white stone such as Botticino creates more depth as this stone has different shades running through it. Up close it does look like a light beige colour but in the mosaic and seen from 5′ – 6′ away it produces the effect of a white.
Best stone; Botticino (a number of types, go for Bott. Classico for the best), Crema Marfil, Biancone looks like a bright white but is veined and has an almost imperceptible green tinge to it.
Black; Nero Assoluto, Zimbabwe Black (granite), Nero Macquina, Toros Black. The last 2 have white veins and a more ‘dusty’ look to the colour. NB Never be tempted to use slate! I was given some in 15mm x 15mm x 10mm and although it looked fine, just like the Nero it was hell to cut. Slate shears, ie the top layer separates from the bottom. Not fun to cut believe me.
Yellow; Giallo Atlantide, Sienna. Yellow is a problem, the most reliable for a good shade is the Giallo Atlantide. There is a good yellow in Travertine Giallo but Travertine is rock formed by the residue from geysers, millions of years ago. This solidifies with air bubbles hence Trav. has a pitted surface. Too much pitting and it will take up any grout you use which is a shame as it does have a good colour.
Dark Green; Verde Guatamala, a really beautiful, deep green. Lovely, lovely colour but quite dark. Against black it can merge. There are lighter greens but these can be quite expensive. Unfortunately I don’t have a decent picture of this one.
So, just a quick list. There are many more coloured stones finding their way onto the market now so this list may alter. It really does depend on the quality of the stone, its availability, how it cuts amongst other considerations.