To summarize the key variations between diamond and topaz;
Although lab-grown diamonds have the potential to be more affordable than mined diamonds, topaz is far less expensive than diamonds.
Topaz's refractive index is lower than a diamond's, giving it a less dazzling appearance.
Although both stones need to be frequently professionally cleaned, topaz requires more maintenance than diamonds.
Topaz is less durable than diamond since it has a hardness of 8 as compared to diamond's hardness of 10.
Overall, diamond is the better choice in terms of hardness, brightness, sparkle, and value, even though it costs a little more.
Although white sapphire and other gemstones more closely resemble diamonds, white topaz is still a good substitute for diamond.