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BUYING GEMSTONE
When buying Coloured Gemstones, it is important to consider the following:-
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Is the stone Natural or Synthetic?
Is the colour natural?
Are there any noticeable inclusions?
Do they affect the durability of the stone? 
How well is the gemstone proportioned?
If the gemstone possesses "Optical Phenomena", is it well defined?
What is the weight of the gemstone?
How do I care for the gemstone?
 
Evaluating Coloured Gemstones
There are "3" factors that determine quality.
Colour
Clarity
Cut
 
Colour
The most important factor in the evaluation of Coloured Gemstones.
The gemstone should be checked under normal daylight, fluorescent light and incandescent lighting noting any colour change.
 
Colour can be described in terms of:
Hue: This is the dominant and secondary colour visible in a stone.
Tone: This is the sensation of the depth or darkness of the colour perceived by the eye.
  Saturation: This is the strength, purity, intensity of the hue present.
 
Hue
The human eye can discern 150 different hues. Basic hue names are: Red, Orange, Yellow, Green, Blue, Violet and Purple.
 
Tone
Tone is described using the G.I.A Tonal scale ranging from 0 (Colourless) to 10 (Black).
 
Saturation
Saturation is assessed on a scale ranging from 0 (Neutral) to 6 (Vivid).
In warm colours (i.e. Red, Orange, Yellow), lower levels of saturation will appear brownish.
In cool colours (i.e. Green, Blue, Violet or Purple), lower levels of saturation will appear grayish.
 
Colour Grading Overview
Thoroughly clean the stone. Hold the stone by the girdle in the tweezers. Look at the stone face-up from about 18" away in strong, diffused, daylight equivalent lighting (with the light 6 to 10 inches above the stone) Estimate the hue of the dominant and secondary colours. Estimate the tone. Estimate the saturation.
 
Clarity
Gemstone should be checked first with the naked eye, then with 10X magnification noting any obvious inclusions or blemishes.
Gemstones are divided into 3 clarity types:
Type 1: Gemstones that are expected to form without inclusions (i.e. Aquamarine). Even minor inclusions will detract from their desirability.
Type II: Form with moderate inclusions (i.e. Ruby and Sapphire). 
Type III : Always found with inclusions (i.e. Emerald)
 
Five factors to consider when "Clarity Grading”:
Nature of the inclusion. (v) Position.
Size.
Colour and Relief.
Number
 
Clarity Classifications
TYPE I
Beryl Topaz Chrysoberyl
Aquamarine Blue Green
Green Beryl Yellow Yellow
Morganite (Pink Beryl) Orange  
Yellow Beryl Pink  
  Red  
     
Quartz Spodumene Tourmaline
Smoky Kunzite Green
  Green  
     
Zircon Zoisite  
Blue Tanzanite  
 
TYPE II
Andalusite Tourmaline
Alexandrite (Chrysoberyl) Blue, Orange, Yellow Parti-coloured (except watermelon)
All Corundum
All Garnets
Iolite All Spinels
   
Quartz Zircon
Citrine, Amethyst, Ametrine Green, Orange, Red & Yellow.
 
TYPE III
Emerald Red or Pink Tourmaline or Watermelon Tourmaline
 
Clean the stone.
Hold the stone by the girdle in tweezers or stone holder.
Look at the stone with the naked eye in the face-up position.
Turn the stone to view from all angles. Look at the stone under 10X with dark field illumination.
Turn the stone to view from all angles.
Use overhead light to check for surface blemishes.
Assign a clarity grade.
 
Cut
Cut includes the proportions and finish of a gemstone.
May also refer to the shape or design in which the stone is cut.
The more expensive the rough, the less likely it is to be well cut due to weight retention.
 
Proportion Grading
Considers:
Beauty
Appeal 
Practicality of outline and dimensions (including the ease in which the stone can be mounted and the presence of excess weight that does not contribute to beauty).
 
Finish Grading
Consider:
Evaluation of the skill and care used in the fashioning process and the gems overall surface condition.
 
Proportions
Three Steps
Face-up Outline
Brilliance
Profile
 
Face-Up Outline
Balance: The equality between corresponding parts of the stone in the face-up position.
Length to Width Ratio: The relationship between the length and the width of a stone.
 
Shape Preferred Acceptable
Rectangular 1.50 - 1.75 1.33 - 1.50 1.75 - 2.00
Marquise 1.75 - 2.25 1.66 - 1.75 2.25 - 2.50
Oval 1.33 - 1.66 1.30 - 1.33 1.66 - 1.75
Pear 1.50 - 1.75 1.30 - 1.50 1.75 - 2.00
Heart 1.00 - 1.25
Appeal: The pleasing quality of the stones face-up outline.
Examples: Misshapen lobes on a Heart Shape.
Undefined point on a Pear Shape.
Flat head and high shoulders on a pear shape.
BRILLIANCE: Light return caused by internal and external reflections.
 
Two Factors that diminish brilliance:
Windowing: A washed out area generally seen through the table caused by "light leakage". 
Extinction: Areas of darkness visible through the crown.
 
Most stones return 65 to 90% of the light.
Dark stones and ones with extreme proportion variances may result in light return below 30%.
 
Profile
Table size : 55 to 65%
Girdle Thickness: Should be of medium thickness, thicker towards the points to prevent breakage. 
Total Depth : 60 to 75%
Crown Height / Pavilion Depth Ratio : 1 : 3 (25% crown to 75% pavilion) or 1 : 2 (33% crown to67% pavilion)
Bulge Factor: Minimal bulge is acceptable in Step-Cuts due to the slight changes in angle necessary from one row of facets to the next.
Balance or Symmetry: The equality between the corresponding parts when viewed from the side or the end.
 
Finish
Polish:  Surface characteristics not included under "Clarity". As a result of the polishing process or wear.
Symmetry: consistency of the shape, positioning and arrangement of facets and the balance of the overall facet design.
 
Gem Store
The following types of Gemstones in the table below are readily available at Real Stone Gem store. However Gemstones of other configurations as per requirements can be delivered on order.
 
To place your orders send email to contact@realstone.in
 
 
 
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