Original Concept:
Black Gold Saw is a girl with red eyes and long black hair. A red flame shoots out from her right eye. She has a pair of curved black horns whose color turns to red as it reaches the tip. Like Dead Master, Black Gold Saw also has skeletal claws. Her outfit is similar to Black★Rock Shooter's except for the design of her jacket and her bikini top; her jacket extends into a worn-out cape which is dyed red at the end.

Her weapon of choice is a large sword with golden blade and a black saw-edge on its reverse side. It has a long handle with a skull-like object on top and a hilt shaped like a crescent; its name is King Saw. She is the "other self" of Saya Irino in the other world.

Black★Rock Shooter (OVA):
In the OVA, her jacket is shorter, and she also wears armored boots with pointed crescent designs. Like all of the "other selves," her eyes have a circular pattern in them. Notably, Black Gold Saw's red flame is not present at all during her appearance.

Black★Rock Shooter (TV):
Her jacket seems to bear a little bit of resemblance to MEFE's clothing. Her sleeve have a red belt attached to it along with two white line running across just above the belt's line. Her jacket is tied together with a white ribbon. Her shorts is a little bit longer and had more details to it. Her belt is also different. Unlike the OVA design, she had no black thigh-high socks although her grieves are pretty much the same, except for some changes, notably at the base of the foot. Her claws are very much the same as that of BRSB now, but, it's still more skeletal. Her King Saw have a new look as well, with a very much shorter blade and a sawblade on the hilt.

Abilities:
Black Gold Saw has demonstrated many abilities in the 2012 anime, more than she ever did in the OVA. She may have some time or reality-altering abilities in terms of the Otherworld, as she managed to stop the destruction of Chariot's world as if she had stopped its time and had seemingly cut reality itself when driving Dead Master into the ground. She also has the ability to create beings, as she creates the strange hooded figures from a watering can. This watering can is also able to sprinkle a mirror-like surface on the ground that shows Saya's memories. She is also able to see things far away using her giant eyes as shown in Episode 1 and Episode 4. She can also summon a massive King Saw out of the ground.

(Source: Black★Rock Shooter Wikia)