It is a layer of ice 
and diamonds.
Deep silver glass 
covered with wire. 
When the cold is cold 
but still liquid and reserved 
for hearts of olives, intangible 
in keeping with logic.
From page 53 of The Complete Guide to the Art of Modern Cookery by Auguste Escoffier, translated by H. L. Cracknell and R. J. Kaufmann (John Wiley & Sons, Inc. 1979).
 
                
              