that isn't the way it goes. as far as grading items goes...
Grey-Normal, Blue-Magic, Yellow-Rare, Orange-Epic. these are your low end common items.
Red-Legend, Light Blue-Legend with Crystal Affix, Green-Eternal (some can also have a Crystal affix, but item stays Green), Purple-Mythic. these are all considered high end rare items. the Legend items drop the most, the Legends with Crystal affixes and the Eternal items are rarer drops, and the Mythic items are crafted by players using a recipe that requires 4 Myth Stones to make.
all items can be modified in some way with Crystals and Myth Stones, except Eternal items. Eternal items double the value of the affixes on them (except for Crystal affixes), but the penalty is that many Crystals can't be used on them, and only Eternal items with sockets can have Myth Stones added to them. there are 2 Eternal items in each class, a MH weapon and a head item, that can have a Mythic affix added to them (think Purple item), but because of the restrictions on the Crystals that can be used, it might take a few tries at crafting to get the affixes you want on them. Crystal affixes are an affix that has 3x value, except the HP/MP on hit, which is 2x, but you can only have 1 of these per item, for 6 total on your equipment (can't put one on pet). you can either find an item with a Crystal affix or use the Obsidian Crystal to put one on your gear.