Hue = Colour
Hue is the colour family, such as red, yellow, green or blue. A gem can also have a secondary colour. For example, a greenish blue gem is mainly blue with some green.
Skyjems-Grading-Guide
SKYJEMS.CASKYJEMS.CA / Gemstone learning guide
Colour & clarity,
made clear.
A beautiful gemstone is more than a colour name. Learn how we describe its colour, what its inclusions mean, and how to read our clarity grades.
Try it yourself
Change one quality at a time.
Choose a hue, then adjust darkness and vibrancy. A darker colour is not always more vibrant.
Blue / medium tone / strong saturation - screen example
This simple screen colour model uses the six saturation names as a learning aid, not as calibrated gemstone grades. Warm hues approach a brownish muted colour; cool hues approach grey. Real gemstone colour is more complex.
Colour, at a glance
Three ways to describe colour.
Hue, tone and saturation describe different parts of the same colour. This is the colour language taught in the GIA coloured-stone system, explained here in everyday terms. [2, 6]
Tone = Darkness
Tone describes how light or dark a colour looks. A light blue and a dark blue can share the same hue. A darker gem is not automatically more vibrant.
Saturation = Vibrancy
Saturation is colour strength. As it decreases, red, orange and yellow tend towards brown; green, blue and purple tend towards grey. Higher saturation looks more vivid. Vibrancy does not mean sparkle.
SKYJEMS.CA teaching illustration. Each example is labelled directly: hue changes the colour family, tone changes darkness, and saturation changes colour strength. These are illustrative examples rather than calibrated grading standards. Screens, printers and lighting can change the colours you see.
Colour also depends on lighting, viewing angle and cut. Some gems show different colours from different directions; this is called pleochroism. Compare gems under the same conditions. [2]
SKYJEMS.CA / Colour guide
Hue = Colour
Start with the colour family. This chart shows example hues only and does not include all hues. Each example has its own colour label. Mixed names show colours between the main families: blue-green sits between blue and green, for example. Hue describes the colour, not its darkness or vibrancy.
SKYJEMS.CA / Colour guide
Tone = Darkness
Read the scale from light to dark. The supplied tone chart runs from 2 to 9. Our guide keeps that sequence and adds plain-language labels. Neutral grey isolates darkness; a coloured gem can have the same tone while keeping its own hue. A higher tone number means darker, not better.
SKYJEMS.CA / Colour guide
Saturation = Vibrancy
Read down one colour lane at a time. As saturation decreases, red, orange and yellow tend towards brown, while green, blue and purple tend towards grey. Read the six numbered steps from Muted to Vivid. Each number has a name, shown in the chart and table below. Stronger colour does not mean greater sparkle.
| Number | Name |
|---|---|
| 1 | Muted: brownish for red, orange and yellow; greyish for green, blue and purple |
| 2 | Slightly Muted |
| 3 | Moderate |
| 4 | Moderately Strong |
| 5 | Strong |
| 6 | Vivid |
Special sapphire colour names
Blue and blue-green
Names such as cornflower, royal blue and teal describe a colour appearance. They do not replace hue, tone and saturation, and they are not a ladder from worst to best. These explanations follow the supplied Lotus Gemology chart and the sources below. [7, 8]
Pastel blue
Light blue with gentle saturation.
Cornflower
Blue between pale pastel and deeper, stronger blues.
Peacock
An intense, electric-looking blue.
Velvet
Rich blue with a soft, velvety appearance.
Royal blue
Deep-toned, vivid blue to blue-violet.
Indigo
Deep blue with more muted saturation.
Twilight
Very deep blue, like the sky after sunset.
Teal
A mix of blue and green.
Educational colour examples. Colour-name background: Lotus Gemology and GIA. These illustrations show ranges, not inventory or laboratory colour determinations.
Special sapphire colour names
Pink, purple, yellow and orange
Pastel pink
A delicate, light pink.
Hot pink
Strong, bright pink; the ruby boundary needs care.
Lilac
Lavender through richer violet shades.
Pastel yellow
Light yellow with gentle saturation.
Padparadscha
A blend of pink and orange, usually light to medium in tone.
Mekong Whisky
A warm, whisky-like yellow to golden-orange appearance.
Educational colour examples. Colour-name background: Lotus Gemology and GIA. These illustrations show ranges, not inventory or laboratory colour determinations.
Clarity / Six grades
What can you see?
We focus on visual beauty and structural durability: what you can see, and whether an inclusion affects the gem. These are our six clarity grades for coloured gemstones. [1]
Unaided eye means without magnification. A loupe is a small magnifier; 10× means ten-times magnification.
LC
Loupe Clean
Unaided view10× detail
No inclusions are visible under 10x magnification. This is the cleanest grade we give a coloured gemstone.
VVS
Very Very Slightly Included
Unaided view10× detail
No inclusions are visible to the unaided eye. The gem is near loupe clean, with only very minor inclusions visible at 10x.
VS
Very Slightly Included
Unaided view10× detail
Very minor inclusions may be visible to the unaided eye. Inclusions are easily visible at 10x. See the eye-clean note below.
SI
Slightly Included
Unaided view10× detail
Some inclusions are visible to the unaided eye. They have little or no effect on the beauty or durability of the gemstone.
MI
Moderately Included
Unaided view10× detail
Inclusions are easily visible to the unaided eye. They may reduce beauty, but do not reduce durability under our definition of this grade.
HI
Heavily Included
Unaided view10× detail
Inclusions are prominent to the unaided eye. They may reduce beauty, durability, or both.
SKYJEMS.CA schematic illustrations. Inclusion details are enlarged or exaggerated to make the differences clear; neither view is drawn at actual size. The 10x windows show selected details, not the whole gem enlarged to a measured scale. These are learning examples, not photographs or grades for actual inventory.
Compare the unaided view with the 10x detail for each grade. Look at visibility, type and location, not just the number of inclusions. A visible inclusion can affect appearance without weakening a gem. Durability requires examination of the actual stone; it cannot be decided from this illustration. [1]
Put it together
Read the whole gemstone.
Beauty and durability are different
An inclusion is a feature inside a gem, such as a crystal, fluid pocket or fracture. Some affect appearance; others may affect resistance to damage. Size, location and type matter, not just the number of inclusions. A clarity grade does not replace advice about care and setting. [1, 4]
Different gems have different expectations
GIA teaching considers the typical inclusion levels of different gem types. Emerald usually contains more inclusions than aquamarine. Our six grades explain what is visible and how it affects the individual gem; they are Skyjems descriptions, not a copy of the diamond clarity scale. [1, 3]
Inclusions can tell a story
Emerald inclusions are often called jardin, meaning garden. Fine needle-like inclusions in sapphire are called silk. These features can be clues to natural origin, treatment or geographic origin when studied by a gemologist. Jardin alone does not prove Colombian origin, and silk alone does not prove Kashmir origin. [1, 4]
Treatment is a separate disclosure
Our treatment disclosure accompanies every clarity grade. A clean-looking gem is not automatically untreated. Read the treatment information and any laboratory report separately from the colour and clarity description. GIA coloured-stone reports focus on identification, detectable treatments and, for eligible gems, origin. Our grades are not GIA laboratory grades. [1, 5]
- Describe the colour. Name the hue, then the tone and saturation. Look at the gem face-up: from the top, as it will usually be seen in jewellery.
- Read the clarity description. Check what is visible to the unaided eye and at 10x. Ask whether an inclusion affects beauty, durability, or both.
- Check treatment and care. Read the treatment disclosure and any laboratory report. Ask about a suitable setting and care for the specific gem.
- Compare fairly. Use the same lighting and a neutral background. View the actual gem when possible; a photo or screen cannot show every colour or inclusion.
The grade describes the gem; your taste guides the choice. A grade is not a promise of value or a guarantee against damage.
Visit us in Toronto
See colour in person.
SKYJEMS.CA
27 Queen Street East, Suite 1011, Toronto, ON M5C 2M6
Monday, Tuesday, Thursday and Friday: 12:00 PM - 6:00 PM
Wednesday, Saturday and Sunday: Closed
Walk-ins are welcome. Appointments are recommended for custom consultations and private viewings.
Book an appointment →Further learning
Sources & references.
Independent SKYJEMS.CA educational guide. Sources checked 3 October 2026.
- Skyjems: The Gemstone Collector's Guide, clarity section
- GIA: Pleochroism in Faceted Gems: An Introduction, Gems & Gemology, Fall 2014, p. 216
- Gems & Gemology: 2006 Gemological Research Conference abstracts, Fall 2006, pp. 130-131
- GIA: Inclusions in Gemstones, Gems & Gemology, Summer 2022
- GIA: Colored Stone Reports & Services
- GIA: Colored Stone Grading Lab Class
- Lotus Gemology: Ruby & Sapphire Color Types
- GIA: Sapphire Quality Factors
- SKYJEMS.CA: Location, hours and appointment booking