well in the US there's 14 colors in the ABA standard and 9 in the APA standard though many are virtually none existent here.
In Germany there is 30 or so colors.
The US ABA standard is
quail
black
lavender
blue
black mottled
cuckoo
mille fleur
blue quail
buff
bb red
porcelain
white
columbian
buff columbian
Personally I have 30 colors and counting, so really if theres a will , you can make any color your heart desires.
In addition to the US colors, Germany also has silver duckwing, gold duckwing, birchen, silver laced, gold laced, silver quail, lavender silver quail, cream milles, red,goldneck,red pyle,blue buff columbian,blue red, blue silvers,and a few others. Not sure what the standard is in the UK, I've heard they are pretty scarce there.
The colors I currently have are
quail, blue quail, dun quail, khaki quail, splash quail, silver quail, bb red, brown red, blue red, crele,cuckoo, blue cuckoo, dun cuckoo, lavender cuckoo, buff,black mottled, dun mottled,white, black, blue, splash, dun,ginger red, mille fleur, blue milles, splash milles, porcelain, lavender, red pyle, columbian, buff columbian, blue buff columbian, lavender buff columbian, lavender barred columbian....might be a bit over 30
Ones I am working on
buff laced, gold laced, silver laced, goldneck, lavender silver quail, khaki, khaki mottled, blue mottled, lavender quail, barred quail, silver duckwing, gold duckwing, birchen, lemon milles and a few others. Then various combos of these in blue, dun, barred, dominate white, mottled and lavender