Making rubies. Part Three: Tweaking the recipe
Making gems. Part three: Tweaking the recipe
With our first batch completed, we should discuss the results. The quartz “rubies” weren’t bad, the calcite ones acceptable, the bamboo manna ones not very convincing, and the alum a downright failure. Generally speaking, the dye did not envelop the stones evenly and also did not seem to adhere that well. And the final step in the recipe, heating the dyed stone in madhuca oil, seemed to be somewhat counterproductive, removing some of the dye rather than enveloping it.
Could we improve results?
We thought that our dye probably was right – or at least followed the recipe. Were the chosen stones perhaps the problem? As noted in the last blog post, we have no way of knowing what the correct “rain-stone” is and thus have to admit that perhaps we did not use the right kind of stone. On the other hand, we felt that our samples of quartz showed reasonably good results.
Still, we figured that there might be a way to improve the adhesion (or even surface penetration?) of the dye, whatever the stone. For this, we drew inspiration from a different tradition: early Graeco-Egyptian alchemy, or more specifically, the recipe collections of the so-called Stockholm Papyrus (ca 4th c. CE). The Stockholm Papyrus details 71 methods for imitating gems. Its recipes follow a particular pattern: First, the stone that will be dyed is corroded and “opened up”, i.e., the surface of the stone is roughened and made porous. Then, the dye is applied.
[Image of leaf 1 of Papyrus Graecus Holmiensis (The Stockholm papyrus) https://lccn.loc.gov/2021668051]
Just a note to justify our use of instructions from a different tradition: The Stockholm Papyrus refers to both Indian crystal and to Indian methods (though not in the context of making rubies), so that it is at least not inconceivable that there may have been historical interaction....
But truth be told, we were just curious to see whether this would make a difference.
I had first come across the Papyrus recipes in a blog post by Marjolijn Bol (see here), posted on The Recipes Project site. Bol followed instructions given in the Stockholm Papyrus to corrode and open up stones and then proceeds with a recipe for making counterfeit emeralds through dyeing the stones with verdigris pigment mixed with an oil. The recipe book contains many recipes for “opening” stones, but this seems to be a fairly simple one:
53. Corroding and Opening Up of Stones (Caley 2008, page 61)
Grind alum and melt it carefully in vinegar. Put the stones therein,
boil it up. and leave them there over night. Rinse them off, how-
ever, on the following day and color them as you wish by use of the
recipes for coloring.
Bol notes in her blog post that she didn’t see much change in her stones, but we thought we would give it a go anyway, since her “emeralds” turned out rather well.
[Image by Marjolijn Bol of her emerald experiment (https://recipes.hypotheses.org/4659)]
Bol used topaz, crystal, and selenite, so we added selenite and topaz to our selection of translucent stones as well. We dropped bamboo manna and alum from our initial selection.
The Stockholm Papyrus also has two recipes for making rubies, by the way: recipes 19 and 31. Recipe 19 is somewhat unclear, but 31 seems relatively straightforward (then again, so do our Indian recipes, until you actually try them out). But just fyi, here’s recipe 31 (Caley 2008: 56):
If you wish to make ruby from crystal, which is worked to any
desired end, take and put it in the pan and stir up turpentine bal-
sam and a little pulverized alkanet there until the dye liquid rises;
and then take care of the stone.
In her 2014 article ‘Coloring Topazes, Crystals and Moonstones’, Bol notes that Greek and Arabic natural philosophers “explain that precious stones are rare, hard, limited in size and, most of all, must have the ability to transmit the visible light”. This last characteristic in particular has “implications for the materials that can be used to make them. Ideally, when imitating a colored, translucent stone, the substances used should also have the ability to transmit the visible light.” (Bol 2014: 112 and 116)
A dye that renders a stone opaque would be useless.
Our fish black fulfills this requirement: it is translucent.
[Filtered fish black (matsyakajjala)]
Our problem with it perhaps rather lay in its not forming a quite thick enough layer to create the right shade of colour. One reason could be that the mixture was not viscous enough to form such a layer. It seemed quite sticky, though. Then, maybe the dye just couldn’t properly attach to the stone. We hoped that roughening our stones would make a difference in terms of dye adherence.
So, Andrew boiled up some high-strength vinegar and mixed it with ground alum. Pro tip: you’ll want good ventilation for this! He added the stones: selenite, topaz, calcite, and quartz and boiled them in the vinegar-alum mixture on low heat for about thirty minutes. He then removed the pan from the heat and allowed everything to cool for a day. The outcome of this was that the surfaces of the calcite and selenite appeared etched, whereas there was no noticeable change to the surface of the quartz or topaz.
["Opening" stones in alum and vinegar]
[Results: slightly etched selenite and calcite, no visible difference in the quartz and topaz]
Andrew proceeded with the dyeing as before: Heating the fish black, i.e., the lac dye in a sand bath, with the madhuca oil also being heated in a separate jar. He added the stones to the lac dye. Noticeably, the selenite was slow to take the dye and was therefore left in the dye the longest. On average, the stones were left in the heated dye for about thirty minutes. The selenite was left in the dye for a couple of hours.
Each stone was then lifted out of the dye and briefly immersed in the heated madhuca oil. The final step was to remove the stones from the oil and leave them to dry.
Well, the “opening” of the stones did not seem to make much of a difference. Perhaps a slightly deeper colour and better resistance to scratching? We can, however, report that topaz yielded similarly good results as the quartz, whereas the selenite was less convincing. Even after being left in the dye for a longer period, it retained a reticulated pattern.
Comparing the previously dyed stones to our new ones, we can mostly note that the dye seems better on both batches the longer it has been left to dry. In the beginning, one could rub the dye off quite easily. Now, it’s harder to get off and requires scratching. Actually, there was a difference between the different types of stones: the dye on the smoother, polished ones (selenite and calcite) came off more easily than on the rougher stones (quartz and topaz). We suppose the dye just got better purchase on their rougher surfaces.
[Scratched calcite: the dye came off very easily]
[Better results with topaz and quartz]
As for the permanence of the dye in terms of colourfastness: time will tell. Several weeks in, there seems to be no fading.
Are our artificial rubies convincing enough? Apart from the polished selenite and naturally smooth calcite, we just used raw, unpolished stones. Perhaps stones already brought into faceted shape would be better? That would probably be less good for dye adherence, though. The further use of the stones is not addressed in the Rasaratnākara (just as the use of the artificial pearls and coral wasn’t discussed in the Rasaprakāśasudhākara.), so we don’t know whether the artificial rubies were supposed to look like raw, uncut rubies, or a more finished product.
We are still puzzled about the ingredients.
The initial boiling in water clearly was aiming at extracting the dye from the lac resin. The resin itself seems to not have been wanted because the water is supposed to be filtered. The borax and natron would dissolve the lac resin, allowing for further extraction of the dye. However, their addition follows the first filtering, so really, there shouldn’t be any lac resin left to dissolve in the water. Perhaps borax and natron were supposed to work as mordants. And indeed, both are traditionally used as fixatives that help bond dye to fibre. Lodhra, our next ingredient, also is used as a mordant in textile dyeing. Maybe it also deepens the red of the lac dye – it is used for intensifying red hues in textiles.
What about the fish skin? Well, boiling down fish skin produces gelatin. And gelatin is known to improve the dyeability and colour strength of fibres. In cotton dyeing, for example, the cotton would be pretreated with gelatin in a pad-dry-cure procedure. It would then be mordanted, and finally dyed. This should lead to higher dye adsorption (at least, this is the finding of a study on using gelatin pretreatment for cotton fabrics dyed with cochineal). The final application of madhuca oil.... well, here I’ve got nothing.
But you see the general trend: the method for preparing dye for making rubies (and also the other gem varieties) follows techniques for dyeing textiles.
In parallel, Bol (2014: 114) notes that the recipes for making gems in the Stockholm papyrus use textile dyeing methods and materials – the Papyrus contains several textile dyeing recipes, so this comparison is a direct one.
The point about textile dyeing is that a dye applied to a textile is supposed to suffuse it. This is one of the differences to paint, which is just meant to cover a surface.
As far as I can tell, pigments used for painting in premodern India were typically made from earth pigments rather than plant materials (indigo being an early exception). Red paint was mostly produced using cinnabar/ vermillion or lead oxide, and the paint carrier would render the paint opaque. The focus seems to have been on strong colour rather than translucency. This would have made paints impracticable for gem imitation. Hence, perhaps, the focus on textile dyeing materials. Perhaps the idea was that the stones dyed with fish black were supposed to be suffused with the dye, that the colour should go through and through.
Well, it does not.
In her study on gem imitation in medieval Europe, Bol describes a pleasing development in medieval art, in which art imitated .... imitation:
European medieval reliquary shrines and panel paintings preserve some of the techniques of Graeco-Egyptian gemstone imitation. For example, a wooden shrine might be covered with gilt copper plaques and set with transparent crystals on reflective pieces of silver foil or on top of blue or red coloured paints, making them look like emeralds or rubies. According to Bol (2014: 126),
“technical research has indeed shown that the panel painters used materials comparable to those used to make gemstone imitations. What is more, they employed these materials precisely to paint imitations of precious stones. Linseed oil ground with verdigris, brazilwood, or ultramarine creates a translucent paint – in art history called a ‘glaze’ that was used to paint emeralds, rubies and sapphires.”
This closes the circle: a glaze for imitating gems in paintings, using materials used before for imitating gems!
I am not familiar with the history of glazes in Indian painting – that might be an interesting avenue for further research. However, for our experiment with making rubies, I think the inspiration for the Jewel Mine’s recipe was textile dyeing, not painting. The one element that does not fit is the final application of oil. That does not happen in textile dyeing, as far as I know. It makes sense in itself, as it gives the stones an extra gleam, at least until it dries. The use of oils is paralleled in the recipes of the Stockholm Papyrus, though there, the pigment is directly mixed with the oil and then used to coat the stones rather than being a separate layer following the initial dyeing.
One final remark: Our rubies look quite convincing, or at the least the quartz and topaz ones do. You can scratch them a bit, and they still hold on to the dye. However, they have one rather obvious characteristic that should have alerted potential buyers: They stink of fish!
I leave to you to decide whether the saying “something smells fishy” goes back to our artificial rubies dyed with fish black......
Here is our final film, in which you can see our fishy rubies glistening in the sun.
Bol, Marjolijn. ‘Coloring Topazes, Crystals and Moonstones: The making and meaning of factitious gems, 300-1500’, in Marco Beretta and Maria Conforti (eds.), F for Fakes: Hoaxes, Counterfeits and Deception in Early Modern Science, 2nd Watson Seminar in the History of Material and Visual Science, Museo Galileo, Florence, June 7, 2013, Science History Publications (Brill Publishers: 2014), pp. 108-129.
Caley, Earle R. and William B. Jensen. The Leyden and Stockholm Papyri. Greco-Egyptain Chemical Documents From the Early 4th Century AD. An English Translation with Brief Notes by Earle Radcliffe Caley. Edited, with a New General Introduction, A Note on Techniques, and a Materials Index by William B. Jensen, Oesper Collections in the History of Chemistry, (University of Cincinnati 2008).