Topaz is a cultivar of dessert apple that was developed in Czech Republic by the Institute of Experimental Botany for scab resistance.Institute of Experimental Botany According to Orange Pippin it is "one of the best modern disease-resistant varieties, with fairly sharp flavour".Orange Pippin
See also Applecrab Opal (apple) – descendant Rajka (apple)
References
"Topaz". ovocnarska-unie.cz