Pearls are considered an important indicator of the quality of a sparkling wine; the process of foaming/pearling is called moussing in German. The finer the rising bubbles are and the more balanced the ring of foam that forms on the surface (la fine collerette de mousse à la surface), the more delicate and sparkling the wine tastes.
During the sensory testing of a sparkling wine, the sparkling quality is also examined. This involves the texture of the bubbles (fine to coarse) and how long the bubbles last in the glass. The finer the bubbles and the longer the play of rising bubbles lasts, the higher the quality of a sparkling wine is judged.
The band of rising bubbles in the glass is called a "cordon". Essentially, the "quality"of the bubbles depends on the type of production of the sparkling wine. The longer the wine is left on the lees after fermentation in the bottle, the finer the bubbles will be. Large bubbles in sparkling wines, on the other hand, are pejoratively referred to as "oeil (yeux) de crapauds" (toad eyes). A normal bottle of champagne with a volume of 0.75 litres contains around 50 million bubbles. In cheap mass products, the carbon dioxide is "blown in", but this only yields very large-volume bubbles. For the carbon dioxide bubbles to rise more in the glass, a mousse point is useful. That a silver spoon in the neck of the bottle prevents the bubbles from escaping is a persistent but nevertheless false rumour. In still wines, a high carbon dioxide content is called effervescent.