The difference was so marked as to be easily seen without the dichroscope.
The difference of colour which it shows in different directions is so marked as to be well seen without the dichroscope.
In the dichroscope the ruby shows two images, one square of a violet red, the second square being a truer and a paler red.
It polarises light, and when viewed with the dichroscope shows a remarkable variety of twin colours.
The student should, if possible, obtain the use of a dichroscope and practice with it on all sorts of stones.
The stone was therefore inspected with the dichroscope and found to possess no dichroism.
The use of a dichroscope would have saved them that error, for the stone is singly refracting.
The dichroscope also serves to detect the false character of doublets and paste imitations, as neither shows dichroism.
The emerald is dichroic, giving in the dichroscope a bluish-green and a yellowish-green image.