yellow diamond cheaper than white diamond.
most important is the colour than clarity. a good quality yellow diamond shd have saturated yellow colour
the best is very intense yellow, then
intense yellow, then fancy yellow, then light yellow
some smaller shops sell bad quality (actually not yellow) yellow diamonds, sell Y-Z colour white diamond as yellow diamonds.
i think fancy yellow is good enough as intense yellow is much more expensive. the cutting is also very important, I have a heart one and an emerald one both GIA cert fancy yellow, with the emerald one IF heart one VS1, but colour of heart one pops much more than than the IF one.
for a GIA cert VS1-2 fancy yellow 1 ct diamond with some small diamonds surrounding the setting, u can get in shop at around 4xk. u can get a bigger discount for yellow diamond than white diamond in big shops e.g. CTF and Luk Fook.