Dichroism

He also studied the orientation of purines and pyrimidines in tobacco mosaic virus and in nucleic acids, by measuring the ultraviolet dichroism of oriented specimens, and he studied, with the visible-light polarizing microscope, the arrangement of virus particles in crystals of TMV and measured dry mass in cells with interference microscopes. ❋ Unknown (1964)

If now a stone that exhibits dichroism is held in front of the square hole and viewed toward the light, two images of the stone are seen, one due to its ordinary ray (which, as was said above, will have one color), and the other due to its extraordinary ray (which will have a different color or shade of color), thus the color of the two squares will be different. ❋ Frank Bertram Wade (N/A)

Brown zircon, while lacking dichroism, is frequently rich and pleasing in shade, and when well cut is very snappy, the luster being almost adamantine, the dispersion being large, and the refractive index high. ❋ Frank Bertram Wade (N/A)

Unfortunately, the eye does not analyze light, but rather blends the effect so that the unaided eye gives but a poor means of telling whether or not a stone exhibits twin colors, or _dichroism_, as it is called. ❋ Frank Bertram Wade (N/A)

They, of course, lack dichroism and are softer than sapphire as well as lighter. ❋ Frank Bertram Wade (N/A)

Not all stones that are doubly refracting exhibit dichroism. ❋ Frank Bertram Wade (N/A)

The dichroism of tourmaline is stronger than that of ruby and more obvious to the unaided eye. ❋ Frank Bertram Wade (N/A)

And as in some real rubies there are found slight hollows corresponding or analogous to the bubbles found in melted glass, it becomes a matter of great difficulty to distinguish the real from the imitation by such tests as hardness, specific gravity, dichroism, and the like, so that in such a case, short of risking the ruin of the stone, ordinary persons are unable to apply any convincing tests. ❋ John Mastin (N/A)

Almandine garnets also show no dichroism and lack variety of color. ❋ Frank Bertram Wade (N/A)

As rubies, emeralds, sapphires, and in fact most colored stones of value, show distinct dichroism, this test is a sure one against these imitations. ❋ Frank Bertram Wade (N/A)

They exhibited dichroism and scratched topaz and it was therefore decided that they at least were genuine. ❋ Frank Bertram Wade (N/A)

The color also lacks variety (owing to lack of dichroism). ❋ Frank Bertram Wade (N/A)

Purple spodumene (kunzite) is pinkish to lilac in shade -- usually pale, unless in large masses, and it shows very marked dichroism. ❋ Frank Bertram Wade (N/A)

It is deep in shade, less red than cinnamon stone, and with marked dichroism, which both brown diamond and brown garnet lack. ❋ Frank Bertram Wade (N/A)

Although strongly doubly refracting, the hyacinth shows scarcely any dichroism and thus lacks variety of color. ❋ Frank Bertram Wade (N/A)

Also, owing to the dichroism of the ruby the red is variable according to the changing position of the stone. ❋ Frank Bertram Wade (N/A)

The test is most useful for emerald, ruby, sapphire, tourmaline, kunzite and alexandrite, all of which show marked dichroism. ❋ Frank Bertram Wade (N/A)

This stone is doubly refracting, exhibiting extremely strong dichroism, especially in the blue and the green varieties. ❋ John Mastin (N/A)

The stronger dichroism of the tourmaline frequently reveals itself to the naked eye, and there is usually one direction or position in which the color of the stone is very inferior to its color in the opposite direction or position. ❋ Frank Bertram Wade (N/A)

The dichroscope also serves to detect the false character of doublets and paste imitations, as neither shows dichroism. ❋ Frank Bertram Wade (N/A)