The inner dots and grains in an emerald are impossible to remove.
Al-Kindi and Nasr write:
The characteristics of an emerald are green colour, lustre and smoothness of surface, especially if something else is placed below it. It is
soft and light, being lighter in volume than all other jewels. Its colour
is unstable over fire, and becomes lime instead, as its essence is light.
Abu Bakr Muhammad bin Zakariyya Razi states that its colour is
like that of verdigris. But this can be conceded only if it is taken out of
copper, not gold mines. Probably he based his idea upon vitriol, as the
origin of the green colour stems from antimony.
In the Lapidary (Kitab al-Ahjar) it has been stated that jasper happens to be its enemy and breaks it, if it should fall upon it. It makes the
stone turbid if it touches it and also abrades it.
As for al-Kindi's emphasis upon its light weight, experience has been
to the contrary, as we have seen even lighter stones, as we shall mention
while describing the weights of jewels with the 100 of the ghnbari ruby
serving as the standard for the volume. The weight of emerald comes to
69'/2.
Emerald mines are found in Egypt at Wahat, Jabal Muqattam and
Bajjah. Abu Ishaq Farisi writes:
Emerald is mined from upper Egypt on both sides of the Nile in the
wilderness quite far from cities. There is no other mine of the stone
on earth.
The Nile flows into Egypt from the south. Galen, in the Kitab
al-Burhan (The Book of Proofs or Demonstrations) has provided the
proof for it through reference to the observatory at Aratastanis. He had
travelled between Aswan and the city of minarets, Alexandria. Aswan
adjoins the frontiers of Upper Egypt and Nubia. There is not much distance between the bank of the Nile and the place where the Nile joins
the sea in Alexandria. If both are situated at the same point from the
meridian, the Nile which flows between the two would flow from the
south to the north and upper Egypt would be its west on both sides,
whereas Jabal-i-Muqattam would be to its east towards Ard-i-Bajjah.
Al-Kindi writes that emerald mines are situated in Upper Egypt in
its eastern towns in the region of the Sudan, behind its city, within the
frontiers of Bajjah near the gold mines between the Nile and the Red
Sea in Jabal-i-Mughal in Nubia. This passage is incorrect. Bajjah is a
city of Egypt, and the area wherein it is situated is not designated as
Sudan. Sudan in common parlance is that region of the Sudan to the
west, from which slaves are brought. There are no mines there except
those of gold. Bajjah has both gold and emerald mines. Mughal
mountains are not situated in Nubia but in the desert between the Nile
and the Red Sea.
