Birthstone Colors – With the exception of diamond, most Birthstones like ruby, sapphire, emerald, spinel, etc., are prized largely on account of the beautiful colors which they display.
Birthstone Colors by Month:
- January Birthstone Color is «Red»;
- February Birthstone Color is «Purple»;
- March Birthstone Color is «Pale-Blue»;
- April Birthstone Color is «White (Colorless)»;
- May Birthstone Color is «Green»;
- June Birthstone Color is «Grey»;
- July Birthstone Color is «Red»;
- August Birthstone Color is «Pale-Green»;
- September Birthstone Color is «Deep-Blue»;
- October Birthstone Color is «Pink (Multicolor)»;
- November Birthstone Color is «Yellow»;
- December Birthstone Color is «Purple (Violet)»;
The quality of Birthstone colors is a most uncertain means of identifying cut Birthstones, as it usually happens that a whole range of tints is shown by specimens of one and the same stone, whilst. specimens of different stones are often so similar in color that it is impossible for any but the most practiced eye to distinguish them.
This fact is impressed forcibly on anyone who inspects for the first time a series similar to that exhibited in the Horseshoe Case.
Of the substances which cause the tints in Birthstones, very little is yet known, a circumstance which is due partly to the very small amounts in which they are present in the specimens, and the consequent difficulty in detecting them by chemical methods, and partly to the high cost of the material necessary for such analysis.
The coloring matters, or pigments, are distributed throughout the mass in a homogeneous manner and are in such a fine state of division that they cannot be detected by the most powerful microscope.
Some have supposed that the pigments and the stone form a solid solution, others that it is merely a case of mechanical mixture, whilst the Viennese mineralogist, Doelter, who has given much attention to this subject, has suggested that in some cases the pigment may be in the colloidal state.
In this way he explained the alteration which often takes place in the color of a Birthstone when it is subjected to heat or other agencies, e.g., radium emanations. Such agencies might possibly convert the colloidal pigment into a crystalline one which would possess a different Birthstone colors. An example of this is yellow topaz which, on being heated, assumes a beautiful pink shade.
Doelter has also examined the behavior of many gemstones towards the emanations of radium and has discovered a number of interesting facts which have, however, not yet been completely explained.
Thus he found that a yellow diamond remained unaltered; a brown diamond was tinged with violet; smoky quartz of pale-brown color, was colored very dark-brown; wine-yellow topaz was colored dark-orange a blue sapphire was colored brown; emerald was practically unaltered, as also was ruby.
In Case 0 will be found a sapphire which, originally colorless, has been tinged with brown by exposure to radium emanations. It may be remarked that this specimen has become much paler during its sojourn in the case. As a result of his study of the influence exerted by heat and radium emanations on the Birthstone colors of minerals.
Doelter has divided the pigments of Birthstone Colors into two classes:
- (a) stable pigments which are present in ruby, diamond and deeply. Colored sapphires, and which are almost insensitive to heat and to radium-emanations;
- (b) H labile” pigments, which are present in pale sapphires, smoky quartz, fluorspar, topaz, zircon, etc., which are altered in some way by heat and radium emanations.
He found that, when such Birthstones were decolorized by heat, exposure to radium usually imparted the original color to the stone. The whole subject is yet in its infancy and for more information the student should consult «Das Radium und die Farben» by Professor O. Doelter, in which a compact summary is given of the results so far obtained.
An interesting point about several colored, doubly refracting Birthstones is that they show distinctly different colors according’ to the direction in which they are viewed.
This phenomenon is called dichroism, and is well seen in such a mineral as green tourmaline which appears almost black when viewed along the prism edge, whilst across the prism edge it appears Light-green. In many cases, however, the dichroism is so feeble that it cannot be observed by the naked eye, and an instrument called a «dichroscope» is then utilized.
On looking at the sky through the instrument we see two images of the slit owing to the double refraction of the calcite. When a dichroic stone is placed in front of the slit, and either the instrument or the stone is rotated, the following facts may he observed. In four positions at 900 from each other, the images of the slit are identical in Birthstone colors, but if the rotation from any such position is continued, a difference in Birthstone colors can be noted which reaches a maximum at 450; the difference then decreases until the next position at which identity of tint occurs is reached, and so on, until the rotation is completed.
Dichroism is due to double refraction and is never observed in singly refracting .stones like garnet and spinel, nor in any colored glass. Colored, doubly refracting stones are sometimes so feebly dichroic that no difference in the tints of the images can be observed, whilst dichroic stones do not exhibit the property if they are viewed along an optic axis.
To eliminate errors arising from this latter fact one should always examine the stone in several directions. It is therefore clear that, whilst presence of dichroism is a sure indication that the specimen is doubly refracting, absence of it does not, imply that a stone is singly refracting.
The following is a list of the dichroic Birthstone Colors:
|Birthstone||Colors||Colors seen in Dichroscope|
|Oriental Amethyst||purple||almost colorless||violet|
|Alexandrite||green||yellow to red|
|Topaz||yellow||pale-pink or colorless||yellow|
|pink||pale-yellow or colorless||pinkish-red|
|Andalusite||green or brown||green or yellowish-green||brownish-red|
|Aksinite||brown||blue||brown to yellowish-green|
|Amethyst||purple||pale-pink to colorless||deep-purple|
|Kunzite||pink or lilac||pale-purple to yellow||purple to pink|
|Enclase||pale green||pale-green to colorless||green|
|Turquoise||Turquoise||whitish-blue to yellowish-brown||deep-blue|
|Zircon||red, orange, yellow, brown||red, orange, yellow, brown||deep-yellow|
|Citrine||yellow||yellow to yellow-purple||brown to yellow|
|Moonstone||blue, orange, brown, green||blue to colorless||blue to green|
|Bloodstone||green+red||green+red to blue+red||blue to green|
|Garnet||any color except blue||any color except blue||any color except blue|
End of Birthstone Colors List