Glyph of Warding, Greater:School (protection); Level 6
Casting Time 10 minutes
Components V, S, M (powdered diamond worth 200 gp)
Target or Area object touched or up to 5 sq. ft./level
Duration permanent until discharged (D)
Saving Throw see text; Spell Resistance no (object) and yes; see text
This spell functions like glyph of warding, except that a greater blast glyph deals up to 10d8 points of damage, and a greater spell glyph can store a spell of 6th level or lower.
Read magic allows you to identify a greater glyph of warding with a DC 16 Spellcraft check.
Material Component: You trace the glyph with incense, which must first be sprinkled with powdered diamond worth at least 400 gp.
Is it 200 gp of diamond dust? 400? Or both?
Ooo, a case where the Archives of Nethys entry is inferior to that in d20pfsrd! That's pretty rare. Anyway, as you'll see in the d20pfsrd version or the PRD, the VSM Components line you quoted is only present in the glyph of warding, not the greater glyph. So the material component line of the latter is an override: 200 gp for the lesser glyph, 400 for the greater.
It's poorly written and ought to be a new Components line reading "V,S,M (400 gp diamond dust)" not an extra line in the spell description.