I have a few comments. First, the IDEAlliance would be quick to correct you in saying G7 "Certification" as they only "certify" G7 Experts who then go out and "qualify" printers as part of the G7 Master Printer program. But getting to your question regarding important components to use for achieving the GRACoL specification and maintaining it over time. One of the key components that I use is a software program called SpotOn! Having done many G7 gigs using handheld spectro-densitometers, I can tell you that it is far easier, and I can achieve a much better result overall using software like SpotOn! Not only will it help when creating and verifying curves (SpotOn! doesn't actually create curves - I use Curve2 for that) but it has a database with tracking and trending which you can monitor over time. This is not an advertisement for said products and there are many other solutions which work similarly - bottom line is invest in something like this and it will make all the difference. Or consider taking it a step farther with a scanning system - both X-Rite (EZTrax) and Techkon (SpectroJet) are new and more affordable solutions.