If you were to somehow assemble a large number of photons together to create a "photon ball," the resulting object would not have a specific color or appearance in the conventional sense.
Photons are elementary particles that are carriers of electromagnetic radiation, including visible light. The color we perceive in everyday objects is the result of the interaction between light and matter. When photons interact with an object, they can be absorbed, transmitted, or reflected. The reflected photons are what we detect with our eyes, and the combination of different wavelengths of light determines the color we perceive.
However, if you were to gather a significant number of photons together in a confined space, they would likely continue to behave as individual particles, rather than forming a solid or tangible object. Their collective behavior would still be governed by the laws of quantum mechanics, where they exhibit characteristics such as wave-particle duality and superposition.
In the realm of quantum physics, photons can be entangled, meaning their properties become interconnected and correlated. While this behavior has been observed in experiments, it is still challenging to control and manipulate large numbers of entangled photons. Even if you were able to create a "photon ball," it would not have a distinct color or appearance as we commonly understand it. Instead, it would likely manifest as a diffuse cloud or swarm of photons, potentially exhibiting complex interference patterns or other quantum phenomena.