A more complete version (with all knives and pattern indexes) of this tool is available
in the OPSkins itemDB
Select your knife
Use the slider to view different fade percentages and their pattern index.
The script calculating the order of the screenshots is not perfect, so there is a good chance that some are in wrong positions. For trading and pricing I suggest you check established databases like csgozone.net
thanks to ju43 for allowing me to use his low poly knife graphic.