A glass ring for current measurements, having a glass body that is arrangeable around an electrical conductor and has a light entry surface and a light exit surface, wherein the glass ring is configured to allow light entering the glass body through the light entry surface to completely circulate around the conductor in the glass body due to reflection at external sides of the glass body, wherein the light exits the glass body at the light exit surface, and wherein the glass ring is formed from a monolithic glass body, wherein the light entry surface is a third side of the glass ring, which comprises two adjacent partial surfaces that are tilted through an angle with respect to one another, wherein a partial surface has a triangular shape, wherein, the glass ring comprises a fifth and a sixth side, which are arranged mutually opposite and in parallel, each having exactly four corners, and the glass ring has a circular cylindrical through-opening, which extends in particular through the fifth and the sixth side, wherein, adjacent to the third side of the glass ring, a second side is arranged comprising, adjacent to the sixth side, a first, trapezoidal planar partial surface, and comprising, adjacent to the fifth side, a trapezoidal partial surface that is composed of two triangular surfaces (7', 7") that are tilted with respect to one another, a second and a third (7") partial surface of the second side, wherein the third (7") partial surface of the second side is tilted through an angle of 2 degrees, with respect to the second partial surface of the second side, wherein, adjacent to the second side, a fourth side, which is constructed from two mutually adjacent partial surfaces that are tilted with respect to one another, with each partial surface having a trapezoidal shape, is comprised, wherein, adjacent to the third side, a first side, which is constructed of two mutually adjacent partial surfaces (6', 6") that are tilted with respect to one another, with each partial surface having a trapezoidal shape, is comprised. wherein the first partial surface of the third side is arranged, to reflect a light beam coming from the fourth side further to the second partial surface of the second side, wherein the reflection to and at the first partial surface of the first side leads to the sixth side, to an exit of the light beam from the glass ring via the sixth side. the glass ring is formed from a monolithic glass body, wherein the light entry surface is a third side of the glass ring, which comprises two adjacent partial surfaces that are tilted through an angle with respect to one another, wherein a partial surface has a triangular shape, wherein, the glass ring comprises a fifth and a sixth side, which are arranged mutually opposite and in parallel, each having exactly four corners, and the glass ring has a circular cylindrical through-opening, which extends in particular through the fifth and the sixth side, wherein, adjacent to the third side of the glass ring, a second side is arranged comprising, adjacent to the sixth side, a first, trapezoidal planar partial surface, and comprising, adjacent to the fifth side, a trapezoidal partial surface that is composed of two triangular surfaces (7', 7") that are tilted with respect to one another, a second and a third (7") partial surface of the second side, wherein the third (7") partial surface of the second side is tilted through an angle of 2 degrees, with respect to the second partial surface of the second side, wherein, adjacent to the second side, a fourth side, which is constructed from two mutually adjacent partial surfaces that are tilted with respect to one another, with each partial surface having a trapezoidal shape, is comprised, wherein, adjacent to the third side, a first side, which is constructed of two mutually adjacent partial surfaces (6', 6") that are tilted with respect to one another, with each partial surface having a trapezoidal shape, is comprised. wherein the first partial surface of the third side is arranged, to reflect a light beam coming from the fourth side further to the second partial surface of the second side, wherein the reflection to and at the first partial surface of the first side leads to the sixth side, to an exit of the light beam from the glass ring via the sixth side.