I have just added QTPro to my site and i think it does what you are looking for. I found the manual in one of the zip files from the contribution page:
Download QTpro 4.3 and go to "New install or update from version before 4.25" directory in the zip file and you should see manual.htm which gives a good idea of what the contribution does for you.
QTPro allows me to modify the stock of each item type (in my case: length, diameter, angle. In your case colour etc).
It also does a low stock report which will show all stock that is below a certain level at that time.
I found that you can set the "low stock level" to be a high value and then you can get a full stock report of everything currently in stock.
Hope this helps,