Emerald month of May

Have you noticed the emergence of all things green of late? We move from the crystalline kaleidoscope filled month of April to the bright yellow-green gild of new oak, hazel and beech leaves at the start of May. From spark, fire and light we float back to earth and emeralds begin to loom large in our imaginations.

From earth to air

Across the UK this turn of the year invokes May revels, May Day, Beltane, Greenmen and Greenwomen. Astrologically Taurus, the cosmic bull, a fixed Earth sign, reaches its zenith. Taurus is all things pleasure and sensory stimulation especially that which comes from earthly nature. Venus, Taurus’s ruler, is about all things love (not just romance and relationships but vocational and hobby love too), money and beauty.

The undisputed gemstone that represents both May and Taurus is emerald. Of all the birthstones in classical and Western lore, emerald has been the least challenged with alternatives – though some exist and there are divergences between global traditions which we should consider. To me, emeralds exude a very feminine energy. In Zoroastrian folk practice, the first week of May is dedicated to the seasonal feast of mid-Spring or Maidyozarem. It is marked in the customary way with food, celebration and togetherness, this time as a relief from the final banishment of Winter and joy in seeing the new shoots we planted at Nowruz or New Year (the Spring Equinox) coming up. We want to see green and welcome light into the house.

In Vedic astrology or Jyotish, emerald (panna) is associated with the planet Mercury and the god Buddha. Similarly to classical/Western astrology Mercury represents intellect, thinking, communication and the source of movement. This is interesting when we think of this time of year, as the month of May is also shared with the zodiac sign Gemini (air sign, things of the mind dominate, ruled by Mercury) which has similar leaning towards learning and intellectual pursuits. In Jyotish, the placement of the gemstone upon the body (e.g. which finger to wear it on if in a ring) and the metal or material it is in mounted in is important. The High Priest’s Breastplate of Jewish tradition, described in the book of Exodus in the Bible, includes pitda, interpreted as emerald, representing Shimon, one of the twelve tribes. For a gemstone to affect its powers effectively, one has to work at ritual purity – a kind of spiritual levelness achieved through thought, pray and ceremony.

Emerald city

So through the month of May our attention is drawn upwards from the rocks and soil up towards the sky. This is quite an apt metaphor for emerald. My love affair with emeralds and deep attraction to their inner, pulsing glow, best when the deep green is tempered with just a hint of blue, started with the 1939 film, The Wizard of Oz. I can’t quite remember how old I was when I watched the film which we had on a video, over and over again. I might even put my fascination with gems down to the way in which the film depicted features like the Emerald City, and Dorothy’s mesmerising ruby slippers. We first glimpse the spectacular columnar structures – not unlike how emerald crystals grow – when Dorothy, Scarecrow, Tin Man and Cowardly Lion reach the end of the Yellow Brick Road and before them lies fields and fields of rose-like flowers. I remember anticipating and being fixated at this scene every time it came up. The famous film was based on L. Frank Baum’s children’s fantasy, The Wonderful Wizard of Oz, published in 1900. I ought to read it and see if the author’s descriptions of the Emerald City compare.

Emerald is the most well-known variety of the mineral Beryl. It is an allochromatic beryllium aluminium silicate coloured by chromium (Cr) and sometimes also vanadium (V). Aquamarine (blue, green-blue), morganite (orange-pink, pink), heliodor (green-yellow, yellow) and goshenite (colourless) are members of emerald’s family. There are other beryls and beryl-adjacent minerals that cut gemmy stones, such as red beryl (audaciously called red emerald by a few) and pezzotaite (pink). Beryl crystals grow mainly in hexagonal prismatic habits––six-sided columns. While aquamarine crystals can grow huge, most emeralds are cut from much smaller crystals.

However there have been some record-breakers, some of which you can see in museums around the world, others are sadly locked away in bank vaults ready for a future gamble at auction. Current emerald talk is around the ‘Amazon Queen’, a 280.84ct (40 x 35mm) octagonal step-cut Colombian emerald in a claw-set pendant. It is being auctioned by Phillips on 13 May 2024. The lab reports confirm its Colombian origin and minor oil in fissures. The combination of its size, superb cut and complex colour immediately suggests this is a stone for very special occasions, and I do hope it sees a life being worn or displayed and enjoyed. However, I must say I am not at all keen on the setting or how it has been presented in some of the promotional materials. It seems to hang like Superman’s kryptonite and there is somewhat of a ‘heavy’ air about it. But what do you do with a rarity like this?

Emeralds are generally a brittle gemstone and commonly included so oiling and fracture filling are common–such as even in the Amazon Queen. There are acceptable tolerances such as minor oiling, a kind of moisturiser, to help sooth those very fine fissures that reach the surface of the stone. Cedar oil used to be used but now more colourless varieties of mineral oil are used. There are unacceptable ones when not declared such as fracture filling with resin where you don’t know how much emerald you are paying for, and how much plastic. Huge care has to be given by lapidaries to analyse fissures and crystal inclusions before cutting. The emerald cut was named for the stone as cutting off the corners of a rectangular stone, and using step facets both makes the most of the stone’s colour as well as protecting it from damage when set and worn. Emerald is approximately 7.5 on the Mohs scale of hardness and it usually has a vitreous lustre owing to its comparatively moderate refractive index (RI) of 1.576 – 1.582. It is a dichroic stone so you will observe distinct blue-green and yellow-green pleochroism. The larger the crystal, the more eye-visible this pleochroism will be. And it is this feature that really sets off the best colour in emeralds.

All in a jardin green

Emerald is probably the most historically globally storied and most simulated of coloured gemstones, from legends about Cleopatra’s mines actually producing peridot, to deceiving Soudé simulants (two pieces of rock crystal, colourless beryl or synthetic spinel sandwiched with a green-coloured glue). Check out gemmologist Sally Spencer‘s article on Soudé emeralds. There are so many emerald simulants that the Chelsea Colour Filter was developed specifically to help pick out true emeralds (although it cannot help with lab grown synthetics like hydrothermal emeralds). The CCF is a great tool to quickly pick out non-emeralds in packets of stones.

What is a truly great emerald somewhat divides opinion. Because emeralds are so often included with multi-phase inclusions, fissures, and crystals like biotite and pyrite, some gemmologists and jewellers feel better green stones are available if clarity is important to you. I remember when first starting my Gem-A Foundation course reading a forum post elsewhere online which completely panned emeralds and refused to ever deal with them. Others lauded the importance of inclusions in emeralds and French-speaking gemmologists called this the jardin or garden as the inclusions resemble all the earthly natural life we celebrate in May. I personally love this analogy and I also feel that an emerald with superb depth of colour, with a nicely formed jardin cut en cabochon (as a dome or ‘sugar loaf’) is a thing of celestial beauty that cannot be rivalled. In fact if you were to spend six or seven figures on a large, perfectly clear, untreated emerald, I would recommend you look at other green stones like a superb green sapphire, green tourmaline, chrome diopside or tsavorite garnet. Imagine, you’d have to walk around with a sign saying “Look, no oil, no inclusions, it really is an emerald!”