Garnets: Fine Jewelry Grading, Origin & January Birthstone Facts


Garnets: The January Gemstone Of Many Colors & Uses

When people think of a garnet, the red January birthstone comes to mind. Garnets are so much more than the average person realizes. They are much more involved in our daily lives than anyone would think. So what makes this colored gemstone so interesting? Let’s take a look… 

What Is A Garnet? 

Garnets are actually a group of minerals. This not only means that there’s more than one type, but that they also come in different colors. Like a sapphire or a diamond, there is a common misconception that these stones can only be one color, but science gives each stone a variety of personalities. Fine jewelry stores, like Hamilton, are wise to this and curate pieces in garnet’s many varieties. So good news, January babies— if red isn’t your color, you can wear your birthstone in another!  

Garnets are found in metamorphic rocks, which are rocks in the Earth’s crust that are altered through intense heat and pressure. Metamorphic rocks are so common that garnets can be found on every continent. The reason why red garnets are the most known is because they are the most common. The rarity of colored garnets comes down to science. Like how the element boron must be present for a diamond to become blue, garnets need certain elements to be present at the time of formation to take on different colors.  

All garnets have the same essential crystal structure: X3Y2(SiO4)3.   

From this equation there are two overall groups: 

  1. Aluminum: X3Al2(SiO4)3 
  2. Calcium: Ca3Y2(SiO4)3 

Garnet Group Mineral Name Defining Element (X/Y) Mohs Scale (Hardness) Color(s)
Aluminum Almandine Fe (Iron) 7-7.5 Red, Brown
Aluminum Pyrope Mg (Magnesium) 7-7.5 Red, Purple
Aluminum Spessartine Mn (Manganese) 6.5-7.5 Orange, Red, Brown
Aluminum Rhodolite (Pyrope+ Almandine) Mn,Fe (Manganese, Iron) 7-7.5 Pink, Red, Purple
Aluminum Malaia (Pyrope + Spessartine) Mg,Mn (Magnesium, Manganese) 7-7.5 Red, Orange
Calcium Andradite Fe (Iron) 6.5-7 Green (Demantoid), Yellow (Topazolite), Black (Melanite)
Calcium Grossular Al (Aluminum) 6.5-7.5 Green, Orange (Hessonite), Red, Pink, Clear
Calcium Uvarovite Cr (Chromium) 6.5-7 Green (Tsavorite)

How Are Garnets Graded?  

As the January birthstone, garnets make lovely fine jewelry. As you will have noticed in the chart above, garnets can range in durability from 6.5-7.5 on the Mohs scale. This means that there is a higher possibility of chipping or scratching on the surface. The lower durability makes grading a garnet that much more important to find the best garnet for your fine jewelry piece.

Grading Garnet Color

Since garnets come in a variety of colors, the idea is to grade each type based on how vivid and saturated each one is.  

Vivid: A green garnet should truly be green. Not blue-green. Not yellow-green. Green

Saturation: How light or how dark is the color? The trick is to find the happy medium. 

Grading Garnet Clarity

To grade a garnet’s clarity, the first step a jeweler or gemologist must take is identifying the type of garnet. This is because the average clarity of a garnet will vary from type to type. Red garnets (almandine, pyrope, and rhodolite) usually don’t have eye-visible inclusions and need a magnifier to see any internal flaws. Other garnets, like the orange ones (spessartine and hessonite) tend to have eye-visible inclusions. As with all colored gemstones, the less inclusions there are overall the better the clarity grading will be. 

Grading Garnet Cut

Unlike emeralds, which are cut into specific shapes to better show their beauty, garnets can be cut into any standard shape to best suit a piece of fine jewelry. Depending on the quality of the garnet and the type a cut may be chosen to better retain more of the gemstone’s natural weight.  

Grading Garnet Carat Weight 

Because different garnets naturally have different densities, the grading is dependent on the type. Some types of garnets are more commonly found in smaller sizes. This makes those varieties with greater carats more valuable than those that are commonly found with larger sizes.  

Garnet History, Lore & Fun Facts

An antique hair comb set with garnets from the Czech Republic & on display in the Smithsonian Institution.
  1. Garnets are perfect gifts for 2nd & 6th wedding anniversaries. 
  2. Garnet comes from the Latin word “granatus” for “seed.” This is because they resemble the pomegranate seeds. 
  3. Step aside friendship bracelets: garnets were once exchanged to show affection and loyalty between friends. Garnets were taken as a sign to ensure that those who had exchanged the gemstones would meet again.  
  4. Garnets were briefly used as bullets in Asia and the American Southwest. 
  5. The gemstone was worn as an amulet for healing. 

Whether you are looking for a birthday or anniversary gift, garnets are as unique as your special someone. Hamilton Jewelers has been curing these fascinating gemstones for over a century. Our expert representatives can help you choose the garnet color and jewelry piece style that best serves suits the recipient. Come into one of our locations to see their beauty for yourself!