ok i'm new at this but after many hours surfing around , i found that when gold is mixed with other alloys the colour is changered from a bright yellow gold ,down all the way to a white. so lets break's it down a little.

nice bright yellow - 100% gold

white gold - 90%- 70% silver 10%-30%% gold ---

whitish gold  - 70% silver 30% gold - sometime copper gets mixed in to which up to 30% which takes 15% of gold and silver away.

pale green yellow - 30%-40$ silver  ,30%-60% gold and copper 30% to 40%.

green yellow - 30 to 15% silver ,70 to 85% gold and copper 30 to 40%

yellowish - 75 to 45% silver, 30 to 70% gold and 40 to 50% copper

yellow - 40 to 5% silver ,60 to 95% gold and copper 40 to 50%

reddish - 90 to 70% gold, and copper 50 to 70%

red yellow - 5% silver, 95 to 90% gold and copper 45%

copper red -70% gold , and copper 70%

please note that its up to , as i to can see that some doesn't add up to 100%

just picture that its a triangle with gold at top , with silver on one side and copper on the other --the more white the more silver , the more reddish the more the copper.

now with prices white gold and red gold show be cheaper ,as its got less gold, the brighter the colour the more gold and more of a price.
now this is to weight

but collectors go by looks

a flat piece would be priced by weight , as for a nugget that looks like something eg. a ducks head( yes that duck's head again ,i missed out on , so pissed about that one)..say the nugget was 0.20 grams - worth around 6$ ,cause it has a nice shape (duck's head) the price would double. i believe this piece jumped up to 25$ , not bad for a 6$ nugget.

i anyways go for the shaped nuggets that look like something eg, head ,tree(some gold wire can look this way) anything that got a good shape.

i been collecting for 6 months now and upto 1/2  an ounce and its still growing
with help from this site and many others ,my love for gold has growing.

if anything in  document is wrong just p.m me and i will fix the post
thanx michael