Campbells' Isabella Rare Topaque is a fortified wine produced in Rutherglen, Victoria, from Muscadelle grapes. The winery, established in 1870, has been producing fortified wines in this region for over 150 years, developing deep expertise in the style. Rutherglen's warm climate with moderate diurnal variation creates ideal conditions for producing high-sugar fruit suited to fortified winemaking. Muscadelle naturally accumulates high sugar levels, a characteristic essential to Topaque production. Campbells maintains a solera system or extended age-mixing program, blending wines from multiple vintage years to create consistency in their Rare category. The non-vintage nature reflects Campbells' approach of selecting base wines from their collection and blending to achieve the house style for Isabella Rare.

Topaque production begins with fully ripened Muscadelle fruit, which is harvested when sugar levels reach optimal ripeness. The grapes are crushed and fermented, with the fermentation interrupted by fortification with grape spirit, raising alcohol to typically 17–18% ABV. This fortification halts yeast activity, retaining residual sugar that contributes sweetness and mouthfeel. Following fortification, the wine undergoes extended ageing in wood, typically in smaller oak vessels that allow gradual oxidative maturation. The solera or blending system ensures consistency across releases by marrying younger wines with older reserve components. Extended oxidative ageing in warm conditions develops the deep amber colour and concentrated caramel and dried-fruit flavours characteristic of Rare quality Topaque.