Engraving can be combined with glass blowing skills to create quite different effects. An example is graal, a technique invented in Sweden. The starting point is a blown glass bubble consisting of one or more layers of coloured glass overlaid on clear glass, known as an embryo. The embryo is engraved, cutting through the layers to reveal the different colours. It is then reheated on a blowing iron and re-blown to the final shape of the object. The invention of this difficult technique was considered the 'holy grail' of glassblowing - hence the name ('graal' is Swedish for grail).