Interesting jade-like shiny patina on Æ24 Olbia coin

[Bonshaw]

I recently purchased a coin that has the strangest reflective glassy green patina. I would love any comments on this. I'm fairly sure that the coin itself is genuine, although it was mis-identified by the auctioneer (Aphrodite Art Coins... not sure about the repute). The coin set me back 32 euros. Here is the photograph from the auctioneer:

Bear with me on this. What I'm really asking for comments on is the jade-like patina. It is really very striking in hand! But I think that I had better say what the coin is first. Feel free to skip the technical details, and look at the video at the bottom!

Aphrodite identified the coin as:

"Skythia, Olbia, c. 250-240 BC. Æ (24mm, 7.71g, 3h). Wreathed head of Demeter l.; c/m: head (of Athena?) r. within round incuse. R/ Axe and bow in gorytos; c/m: two foreparts of bull l. HGC 3.2, 1889-90. Green patina, VF - Good VF
Hoover, O. Handbook of Coins of Macedon and Its Neighbors, Vol. 3, Part II: Thrace, Skythia, and Taurike, Sixth to First Centuries BC. HGC 3.2. (Lancaster, 2017)."

It was clear to me that the coin is actually a fairly rare Olbian coin with radiate facing head of Helios on the obverse, and conjoined parts of two horses on the reverse (HGC 3.2,1892). But interestingly, it was overstruck on an older Demeter/Axe-and-bow coin (HGC 3.2, 1890). The obverse strike was so weak, that you mostly see the left half of Demeter's head (the face), although  the rays around Helios are evident on the right hand side. For reference, here is a clean non-overstruck version of this coin that I picked up from a CGB.FR auction (also the auctioneer's photo):

And here is an image of the Demeter /axe and bow type that provided the flan for the overstrike, this time from an Astarte auction (not my coin) (https://www.acsearch.info/search.html?id=13107693), except that the inset small face on the right is right-facing on the overstruck coin rather than left-facing (shown here).

Greek
SKYTHIA. Olbia. Circa late 3rd-2nd centuries BC. Bronze (Bronze, 20.87 mm, 6.49 g). Head of Demeter to left, small head of Perseus to left behind. Rev. Axe and bowcase; [OΛ]BIO above; [Δ]IOΣ below. SNG BM Black Sea 599. HGC 3.2, 1890. Dark patina. Very Fine. Scarce.
AE

All of that is just to provide context for this coin; the patina is what I'd really love to get comments on, but the coin itself is a distraction if not explained. At the bottom is a video of the coin in hand. I hope that the video comes through - let me know!

The patina isn't just green on the obverse. It looks like jade, or green glass, so shiny. Obviously the patina can have been applied in modern times. But I have never seen a patina like this. Is it normal?

Thanks for any comments!

 

 

 

Edited January 5 by Bonshaw

[Bonshaw]

Also, please post images or video if you have coins with glass-like or jade-like patina, I would love to see them!

Not just Jade colored (those are cool too), but shiny and hard like jade or glass...

Edited January 5 by Bonshaw

[expat]

I think it is nice to see patinas that are not the norm. I have a very similar patination on this coin from Troas. Beautiful green, rock hard and shiny.

[JAZ Numismatics]

I think the patina is natural but it's probably been polished

[Roman Collector]

I like glossy green patinas. Here are a couple such coins in my collection. 

Antoninus Pius, AD 138-161.
Roman orichalcum sestertius, 23.16 g, 29 mm.
Rome, AD 142.
Obv: ANTONINVS AVG PIVS P P TR P COS III, laureate head right.
Rev: ANNONA AVG S C, Annona standing right, between modius and prow, holding corn ears and out-turned cornucopiae.
Refs: RIC 597; BMCRE 1228; Cohen 37; RCV 4147; UCR 502. 

Faustina II, 147-175 CE.
Roman orichalcum sestertius, 24.67 g, 31.1 mm, 7 h.
Rome, June 152 - autumn 154 CE.
Obv: FAVSTINA AVG PII AVG·FIL·, bare-headed and draped bust right (Beckmann type 2 hairstyle).
Rev: CONCORDIA S C, Concordia seated left, holding flower and resting elbow on cornucopiae set on globe under chair.
Refs: RIC 1374a; BMC 2175-76; Cohen 57; RCV 4713; Strack 1315.

[CPK]

Like @JAZ Numismatics I think it is natural. Beautiful!

[-monolith-]

6 hours ago, JAZ Numismatics said:

I think the patina is natural but it's probably been polished

Sealed with Renaissance Wax. I purchase a lot of Greek and Provincial coins and most have been treated with Renaissance Wax to make them darker and help highlight the coins details. I personally prefer untreated, dull, coins but the wax can be removed with acetone. Here are some sealed and unsealed green patina coins from my collection. 

 

 

 

[kirispupis]

I have a number of coins with glossy patina, including this one which is glossy green. I'm not sure whether this is a natural patina, or if the seller applied it afterwards. There are a number of sellers known for adding patinas to their coins.

Troas, Ilion (Troy)
301-281 BCE
AE 9mm 0.81g
Helmeted head of Athena right, wearing crested Attic helmet decorated with a wreath /
IΛ-I; hydria.
Bellinger T3; SNG Cop 346

 

Here's one of my favorite green coins.

Marcus Aurelius AE Sestertius / Victory over Germany
172 CE
31.20mm 27.18g
Obverse: M ANTININVS AVG TR P XXVI, laureate head right
Reverse: IMP VI COS III, Victory standing right hanging shield inscribed VIC/GER on palm tree; S-C across fields
RIC III 1029 Rome
Ex CNG 2013

 

And here's my example of the Olbia undertype of your coin. It has a glossy black patina.

Skythia, Olbia
Æ 10.54g, 24mm, 9h.
Circa 330-320 BCE
Horned and bearded head of river god Borysthenes to left / Axe and bow in gorytos, ΟΛΒΙΟ upwards to right, Δ to left.
SNG Moskau 978-82; SNG Stancomb -; SNG BM Black Sea 457-9; HGC 3.2, 1887.
Ex collection of GK