Gem of the Month

Each month this section will feature either a topic of interest to gem lovers or one special gemstone with background on the material and its value.

Go to: Homepage -- what's new at ACS -- monthly specials and discounts -- "buried treasures" -- BWS/FS jewelry designs -- gem topic of the month -- gem topic archive -- birthstones -- ask Barbara -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- setting these gems -- free gemology course

 

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Larimar

Pectolite had been thought of as a fragile, white or grey mineral of little gemological significance, that is, until a compact blue form was first mined in the 1970's. This material was named "Larimar" by a local miner, Miguel Mendez, (in honor of his daughter, Larissa, and the Spanish word for sea: mar), And it has changed the world's opinion of the gem value of pectolite. Although technically still properly referred to as blue pectolite by mineralogists, the public has been captured by the more evocative name, and Larimar is well on the way to becoming the accepted variety name for this lovely material.

Pectolites are hydrated silicaeous secondary minerals containing sodium and calcium, found in volcanic deposits (and in alluvium washed from them). In this particular deposit copper impurities, and replacement of some of the calcium with cobalt accounts for the varying blue hues, which range from light to medium dark sometimes with a hint of green. Most stones are mottled with an attractive honeycomb pattern of lighter and darker blues.

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[Larimar gems: a high quality mottled blue piece, one in a more uniform robin's egg blue, a mottled slightly greenish blue piece]

It was the robin's egg blue color of the best specimens along with their compact, dense nature which allowed these pieces to achieve a high polish, and exhibit the toughness of jade, that took the gem world by storm. The only location on Earth that yields this blue pectolite is a less than one kilometer square area of mountainside overlooking the Caribbean Sea in the southwest of the Dominican Republic. Mining conditions are hazardous and primitive. By no means are constant supplies assured for the future.

Use and Care:

Although on the soft side, the fibrous nature of this gem makes it quite tough, and suitable for many jewelry uses, with the possible exception of daily wear rings. No special precautions apply in regards to cleaning, although non-abrasive cleaners are recommended. Slight fading with prolonged exposed to bright light has been reported, but this effect should be insignificant in jewelry normal useage.

Larimar gems are usually set in silver which compliments the blue color very well, but especially fine pieces are occasionally seen set in white or even yellow gold.

[Larimar and sterling silver jewelry: two pendants and a bracelet]
Value Factors

So little has been written about this gem that no firm value criteria have been established. It is safe to say that compared to turquoise of equivalent color, the gem is a bargain. In general, the stronger and purer the blue color the higher the price a piece commands. The degree of compactness is important as well in determining the fineness of polish on the finished stone. Large pieces are also at a premium. Lower quality material is often very light or greyish with large areas of white or reddish matrix. As a single source gem, prices are virtually assured to increase in the future as the deposit is ultimately depleted.


Gemological Properties:

Makeup: Sodium, Calcium Silicate --Pectolite: NaCa2Si2O5(OH)

Hardness: 4.5-5.5

Toughness: good, especially if compact and fibrous

Crystal System: triclinic

Luster: vitreous

Density: 2.74 - 2.88

RI: ~ 1.60

Cleavage: splintery
Stones Currently Available:

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Go to: Homepage -- what's new at ACS -- monthly specials and discounts -- "buried treasures" -- BWS/FS jewelry designs -- gem topic of the month -- gem topic archive -- birthstones -- ask Barbara -- key to all the codes used on the ACS site -- definitions of terms used on the ACS site -- how to order -- about ACS -- setting these gems -- free gemology course