Determination of natural ruby by inclusions, using the example of the vietnamese ruby

1.

Determination of natural ruby
by inclusions. Using the
example of the Vietnamese
ruby

2.

Photo 1

3.

Visual purity of ruby
Photo 2

4.

Photo 3. Changing the color of the ruby when changing the illumination

5.

Structural inhomogeneities (twinning) in natural ruby
Photo 4

6.

Photo 5 Panorama of inclusions (magnification x200). Rutile cotton
inclusions in ruby, clouds of rutile particles

7.

Photo 6
A fragment of the
panorama of
inclusions in ruby
when changing the
angle and
illumination.
The photo shows
characteristic circles
or arcs around some
inclusions

8.

Photo 7
Fragment of the
panorama of
inclusions in ruby
at the next change
of angle and
illumination

9.

Comment to photo 7:
When magnified in a computer, two-phase fluid inclusions are
visible in the photo, as if straddled by gas bubbles (gray-blue
bubbles are located in the bulges of disc-shaped and oval
cavities of red color), as well as round brick-red minerals. In
the right part of the image, a circular channel inclusion is
visible, which, like some other cavities in this stone, is
significantly affected by corrosion, with the crystallization of a
yellowish-orange substance, most likely iron oxide compounds
and the release of gray-blue gas bubbles, most likely carbon
dioxide.

10.

Photo 8
Dense milky clouds
consisting of the smallest exsolution
particles of rutile.
According to the GIA methodology
, dense milk clouds are
a diagnostic sign of Vietnamese rubies
(fragment of the original photo 5,
at this magnification, it is impossible
to confuse a haze of the smallest solid
particles with a cloud of gas bubbles)

11.

Photo 9
Inclusions of short
rutile needles,
including in the form
of arrowheads

12.

Photo 10
Panorama of some
corroded solid
(mineral)
inclusions in ruby.
Some fragments of
the mineral hematite
are limonitized and
have yellow-brown
films of hydrated iron
oxide

13.

Hematite minerals (ore fragments) are gray in color with a metallic luster and bluish
streak in the form of irregular lamellar grains with an uneven, stepped or shell fracture.
The protogenetic nature of inclusions in ruby is indicated by the corrosion (dissolution of
the surface) of the minerals of the inclusion. The undissolved minute particles of iron
oxide around the minerals indicate the absence of temperature treatment
Photo 11
Photo 12
Photo 13

14.

Photo 14
Photo 15
Cavities in ruby filled with multiphase inclusions (several crystalline phases, fluid, blue
gas bubbles that are not transparent in transmitted light). The walls of the cavities are
stained with the presence of iron oxide. Examination and shooting in polarized light made
it possible to see inclusions hidden in opaque cavities (not visible in photo 5). They both
testify to the natural origin of the stone and the absence of its heat treatment

15.

Photo 16
The protogenetic nature of the solid
inclusion in the ruby is indicated by the
presence of tension cracks around it
(tension halo), which are visible at
certain positions of the stone and angles
of incidence of light. Examination and
shooting in polarized light made it
possible to see inclusions hidden in
opaque cavities of ruby (for example, in
photo 5)

16.

Photo 17
Photo 18
Primary two-phase fluid inclusion in ruby
(fluid and blue gas bubbles that are not
transparent in the transmitted light) with
decrepitation halos surrounding them.
Inclusions indicate both the natural origin of
the ruby and the absence of its heat
treatment

17.

Photo 19
Photo 20
Primary three-phase
fluid inclusion in ruby
with the presence of
mineral phase.
The walls of the cavity are stained
with the presence of iron oxide.
Inclusions indicate both the natural
origin of the ruby and the absence of
its heat treatment

18.

Photo 21
A fragment of a panorama of
inclusions in ruby under
polarized light. In the middle
part of the image, a vertical
channel inclusion is visible,
feeding the growth of a small
crystal inside the ruby, passing
through the entire image, which
is significantly affected by
corrosion, with the
crystallization of a yellowishorange substance,
most likely iron oxide
compounds

19.

Photo 22
Photo 23

20.

Photo 24
Photo 25

21.

Comment on photo 22-25 (22.23 - normal illumination, 24.25 - polarized light):
The lines (stripes) visible in the photographs are on the surface of the ruby (the results of
manual cutting and polishing), in no way
can they be mistaken for ruby growth lines.
Some scratches are a continuation of the well-visible chips on the ribs. The strips do not
cross faceted borders, the distances between them are different, the strips themselves are
of different thickness, are not contrasting and are not concentric.
On separate sections of faces (facet) the stripes (scratches) are located at different angles,
intersect and smooth out, erase each other. This can be seen in the photos in polarized
light, which were required in order to see inclusions hidden under normal illumination in
opaque cavities (microscopic cracks inside the stone)

22.

Photo 26
Photo 27
Photo 28
Photo 29
Photo 30
Photo 31
Channel inclusion (former
growth tube)
by sections. The channel
connection is largely corroded
and filled with the formed
as a result of crystallization by
a substance. These photos are
also interesting because they
show halos of decompression
of fluid inclusions in ruby,
consisting of a transparent
liquid. As you know, gas
bubbles in passing light are not
transparent

23.

The dimensions of the stone (approximately): length and width 10x9 mm, thickness 5
mm, based on linear dimensions, taking into account the features of the cut, its weight is
about 5 carats. There are no inclusions (turbidity) visible to the naked eye, the stone is
visually completely clean, homogeneous and transparent. The color of the stone is red of
medium saturation with a slight purple tint.
All inclusions are concentrated in one area of the stone with a diameter within one
millimeter. The presence of these inclusions indicates both the natural origin of the ruby
and the absence of its heat treatment.
The detected inclusions correspond to inclusions characteristic of Vietnamese rubies:
(https://www.gia.edu/gems-gemology/winter-2019-ruby-geographic-origindetermination ).
Vietnamese rubies are found in the mineralized marble belt, which is almost identical to
the geological conditions in which rubies are found in the Mohawk region of Myanmar,
according to the GIA conclusion, high-quality Vietnamese rubies are no worse than
similar rubies from Myanmar.
Author — Sergey: [email protected], presentation in Russian: https:pptonline.org/1339711