Insulating glazing unit, in particular for a climate chamber

An insulating glazing comprising at least two glass sheets that are spaced apart by at least one air- or gas-filled cavity, at least one spacer that is arranged at a periphery of the two glass sheets and that keeps the two glass sheets spaced apart, the at least one spacer being a transparent spacer made of transparent plastic and placed on at least one of the sides of the glazing, and a first leaktight barrier that is leaktight to water, formed by at least one structural seal, a material of which is watertight, and a second leaktight barrier that is leaktight to gases and to water vapor, the first and second leaktight barriers being made of transparent material, and wherein the transparent spacer comprises on at least one of its internal and external faces, the internal face and facing the gas-filled cavity and the external face being opposite the internal face and facing an exterior of the insulating glazing, a transparent thin coating which has a thickness of at most 500 μm and constitutes the second transparent leaktight barrier that is leaktight to gases and to water vapor, the transparent thin coating and the transparent spacer forming a single assembly.