What is necessary for yellow to reddish brown topaz to attain a treated pink color?

The transformation of yellow to reddish-brown topaz into a treated pink color primarily involves exposing the gemstone to irradiation, which typically alters its color properties. Among the options, the necessary condition for achieving the pink hue in treated topaz is achieved through the influence of blue to slightly greenish blue color traits.

In gemstone treatments, utilizing specific spectral properties allows the inherent yellow tones to shift to shades of pink. This color change occurs because the treatment process affects the electronic configuration within the crystal structure, specifically targeting the presence of trace elements and affecting their light absorption characteristics.

The other options do not accurately represent the process required for changing the color of topaz to pink. High temperature treatment and exposure to sunlight may influence other gemstones or colors, but they are not necessary for creating the desired pink hue in yellow to reddish-brown topaz. The combination with carbon is unrelated to this particular treatment affecting topaz colors. Thus, focusing on the presence of the specific color spectrum is essential for this transformation.