Silmarillion Chapter 7: Of Fëanor and the Unchaining of Melkor
For Fëanor, being come to his full might, was filled with a new thought, or it may be that some shadow of foreknowledge came to him of the doom that drew near; and he wondered how the light of the Trees, the glory of the Blessed Realm, might be preserved imperishable. Then he began a long secret labour, and he summoned all his lore, and his power, and his subtle skill; and at the end of all he made the Silmarils.
Here is the beginning of the end for the peaceful days of the Elves. Never before nor after would anything as beautiful or tragic as the Silmarils ever be created again. Not an easy thing to illustrate, so I kept it pretty abstract.
On the topic of Fëanor’s appearance: the Noldor are only described as being more muscular than other Elves, and having darker hair and features. Additionally, we know the Noldor resemble the human House of Bëor, who are described as having brown, “swarthy” skin and dark features. Tolkien’s characters are often all portrayed as white Anglo-Saxon, but in reality this frequently conflicts with his ethnic descriptions.
Noldor Warriors - On the right is a generic soldier, while on the left is another illustration of Galadriel. While best known for her more regal role in Lord of the Rings, in this era, Galadriel is militant and ambitious, ready to defy the Valar and claim a kingdom of her own in Middle-Earth.