An apparatus for optical testing of a sample of optical material, the apparatus comprising: (a) an assembly comprising: (i) an optically transparent general-cylinder having an interior partially filled with a bulk material portion from an interior surface of said general-cylinder toward a center axis of said general-cylinder, and said interior having a hollow portion extending from an opposite interior surface of said general cylinder and including said axis, said hollow sized to receive at least a core area of the sample of optical material, (ii) a receptacle including said hollow, said receptacle sized to receive at least a portion of the sample of optical material, and said receptacle sealed for receiving a quantity of fluid, such that said fluid surrounds and is in contact with at least said core area, and is in contact with said general-cylinder and at least a portion of said bulk, and (b) an optical arrangement: (i) aligned with said axis, (ii) including an optical source providing an optical light beam normal to a circumferential surface area at a first side of said general-cylinder, and (iii) including an optical detector accepting an output signal, said output signal from said optical light beam impinging on said core area and transmitted through or reflected from the sample, said optical detector normal to a circumferential surface area of said general-cylinder. (a) an assembly comprising: (i) an optically transparent general-cylinder having an interior partially filled with a bulk material portion from an interior surface of said general-cylinder toward a center axis of said general-cylinder, and said interior having a hollow portion extending from an opposite interior surface of said general cylinder and including said axis, said hollow sized to receive at least a core area of the sample of optical material, (ii) a receptacle including said hollow, said receptacle sized to receive at least a portion of the sample of optical material, and said receptacle sealed for receiving a quantity of fluid, such that said fluid surrounds and is in contact with at least said core area, and is in contact with said general-cylinder and at least a portion of said bulk, and (i) an optically transparent general-cylinder having an interior partially filled with a bulk material portion from an interior surface of said general-cylinder toward a center axis of said general-cylinder, and said interior having a hollow portion extending from an opposite interior surface of said general cylinder and including said axis, said hollow sized to receive at least a core area of the sample of optical material, (ii) a receptacle including said hollow, said receptacle sized to receive at least a portion of the sample of optical material, and said receptacle sealed for receiving a quantity of fluid, such that said fluid surrounds and is in contact with at least said core area, and is in contact with said general-cylinder and at least a portion of said bulk, and (b) an optical arrangement: (i) aligned with said axis, (ii) including an optical source providing an optical light beam normal to a circumferential surface area at a first side of said general-cylinder, and (iii) including an optical detector accepting an output signal, said output signal from said optical light beam impinging on said core area and transmitted through or reflected from the sample, said optical detector normal to a circumferential surface area of said general-cylinder. (i) aligned with said axis, (ii) including an optical source providing an optical light beam normal to a circumferential surface area at a first side of said general-cylinder, and (iii) including an optical detector accepting an output signal, said output signal from said optical light beam impinging on said core area and transmitted through or reflected from the sample, said optical detector normal to a circumferential surface area of said general-cylinder.