The Tables of the Law as they are widely known in English, or Tablets of Stone, Stone Tablets, or Tablets of Testimony (in Hebrew: לוחות הברית Luchot HaBrit - "the tablets [of] the covenant") in the Hebrew Bible, were the two pieces of stone inscribed with the Ten Commandments when Moses ascended Mount Sinai as written in the Book of Exodus. Exodus 31:18 refers to the tablets as the "Tablets of (the) Testimony".
According to the Bible, there were two sets. The first, inscribed by God, (Exodus 31:18) were smashed by Moses when he was enraged by the sight of the Children of Israel worshipping a golden calf (Exodus 32:19) and the second were later cut and rewritten by Moses. (Exodus 34:28)
According to traditional teachings of Judaism in the Talmud, they were made of blue sapphire stone as a symbolic reminder of the sky, the heavens, and ultimately of God's throne. Many Torah scholars, however, have opined that the Biblical "sapir" was, in fact, the lapis lazuli (see Exodus 24:10, lapis lazuli is a possible alternate rendering of "sapphire" the stone pavement under God's feet when the intention to craft the tablets of the covenant is disclosed Exodus 24:12). 
According to the bible, both the first shattered set and the second unbroken set were stored in the Ark of the Covenant (the Aron Habrit in Hebrew).
In recent centuries the tablets have been popularly described and depicted as round-topped rectangles but this has little basis in religious tradition. According to Rabbinic tradition, they were rectangles, with sharp corners, and indeed they are so depicted in the 3rd century paintings at the Dura-Europos Synagogue and in Christian art throughout the 1st millennium, drawing on Jewish traditions of iconography.
The rounded tablets appear in the Middle Ages, following in size and shape contemporary hinged writing tablets for taking notes (with a stylus on a layer of wax on the insides). For Michelangelo and Andrea Mantegna they still have sharp corners (see gallery), and are about the size found in Rabbinic tradition. Later artists such as Rembrandt tended to combine the rounded shape with the larger size. While, as mentioned above, Rabbinic tradition teaches that the tablets were squared, according to some authorities, the Rabbis themselves approved of rounded depictions of the tablets in replicas so that the replicas would not exactly match the historical tablets.
According to the Talmud, the length and width of each of the Tablets was six Tefachim, and each was three Tefachim thick - respectively roughly 20 and ten inches, though they tend to be shown larger in art. Also according to tradition, the words were not engraved on the surface, but rather were bored fully through the stone.
In Jewish religious tradition, the arrangement of the commandments on the two tablets is interpreted in different ways. Rabbi Hanina ben Gamaliel said that each tablet contained five commandments, "but the Sages say ten on one tablet and ten on the other". Because the commandments establish a covenant, it is likely that they were duplicated on both tablets. This can be compared to diplomatic treaties of Ancient Egypt, in which a copy was made for each party. But the tablets may have contained not only the Ten Commandments but also additional precepts and words as can be inferred from the verses Exodus 31:18, Exodus 34:1, Exodus 34:27-28. 
Replicas of the tablets, known as tabots or sellats, are a vital part of the practice of Ethiopian Orthodox Church, which claims that the original Ark of the Covenant is kept in the Church of Our Lady Mary of Zion in Axum.
These tablets are not broken in the Quran, but picked up later: