Excellent Arkansas cluster - showed us its' HALF INCH diamond window - and two OTHER [smaller] diamond window crystals as well!
From the closed mines at Clear Creek, it's 3x 4x 2 1/2" spread out. The widest doubly-terminated crystal is 1 7/8x 3/4x 3", has a rare 8-edged channel face, a 7h face and the tiny diamond as its' 8h, very rare face. The biggest, with the diamond window [there is no other kind of window], is 7/8x 3" with rainbow penetrators. Another crystal is 7h faced, one crystal has none.
A great set of unusuals for your collection, the concave underside has drusy and yet more nascent quartz with warm beige areas of included pale iron. No damage.
Each One The Only One.tm