According to the K&F concept homepage, the surface treatment for this adapter is "anodized" and that means anodized. Anodised layers are used to improve the appearance and functionality of the surfaces of aluminum materials; With the adapter, the aspect of wear resistance (contact surface to the camera) should play an important role (a black lacquered connection surface would probably start to "dissolve" after a few adaptation processes). 

Could you please update us your full Minolta lens model ?as Minolta has MD MC and AF mount, K&F Concept MD-M4/3 is suitable for: Lens: Minolta MD MC Mount lens(not for Minolta AF mount: KF06.157) Camera: Micro 4/3 (MFT) mount mirrorless camera like Olympus PEN, OM-D series, Panasonic Lumix DMC-G1, G2, G3, G10, GX1, GH1, GH2, GF1, GF2, GF3, GF5, GH4, Panasonic AG-AF100 Mirrorless Digital Cameras, Black Magic Pocket Cinema Camera (BMPCC) 

K&F have a list of which adapter will work for each lens to camera combination they support 

hello panasonic lumix g7 is m3/4 mount, so the adapter ring could not work for panasonic lumix g7 

1. You could consult us or search the mount information online
2. You could find the mount information on your instruction book when purchase the lens/camera
3. The mount information may be showed on front of the lens, side of the lens, rear of the lens or on the lens cap, usually it is a 2 or 3 letter code such as: CN, FD, OM, MAF, NK, N/AIS or F/AX