Yes, Opal is the gemstone for the planet Venus and according to the astrologers, the color & intensity of the fire affect the metaphysical attributes of an opal gemstone. The color of fire shows dominance in the flashes and is more likely to deliver benefits of the associated planet.
For instance, a prominent red color represents more fire, and the aligned opal harnesses the energies of the sun whereas a dominant blue flash provides the positive energies of the planet Saturn. Although, opals that hold a complete spectrum of colors in the fire are considered the best from the astrological perspective.