Question 140: Which is the eighth commandment?

Answer: The eighth commandment is, Thou shalt not steal.

Question 141: What are the duties required in the eighth commandment?

Answer: The duties required in the eighth commandment are, truth, faithfulness, and justice in contracts and commerce between man and man; rendering to everyone his due; restitution of goods unlawfully detained from the right owners thereof; giving and lending freely, according to our abilities, and the necessities of others; moderation of our judgments, wills, and affections concerning worldly goods; a provident care and study to get, keep, use, and dispose these things which are necessary and convenient for the sustentation of our nature, and suitable to our condition; a lawful calling, and diligence in it; frugality; avoiding unnecessary lawsuits and suretyship, or other like engagements; and an endeavor, by all just and lawful means, to procure, preserve, and further the wealth and outward estate of others, as well as our own.

Question 142: What are the sins forbidden in the eighth commandment?

Answer: The sins forbidden in the eighth commandment, besides the neglect of the duties required, are, theft, robbery, man-stealing, and receiving anything that is stolen; fraudulent dealing, false weights and measures, removing land marks, injustice and unfaithfulness in contracts between man and man, or in matters of trust; oppression, extortion, usury, bribery, vexatious lawsuits, unjust enclosures and depopulations; engrossing commodities to enhance the price; unlawful callings, and all other unjust or sinful ways of taking or withholding from our neighbor: What belongs to him, or of enriching ourselves; covetousness; inordinate prizing and affecting worldly goods; distrustful and distracting cares and studies in getting, keeping, and using them; envying at the prosperity of others; as likewise idleness, prodigality, wasteful gaming; and all other ways whereby we do unduly prejudice our own outward estate, and defrauding ourselves of the due use and comfort of that estate which God has given us. (Here)

Seeing movies like "Blood Diamond" puts the Eighth Commandment in a truly new perspective. Especially relevant, is the way the diamond merchants ("allegedly") buy up diamonds and then hold on to them, creating an aritificial scarcity in order to keep prices high. Talk about "inordinate prizing and affecting worldly goods".

I first heard about all this back when I was in the Army and resolved never to buy a diamond. What concerns me however is the possibility that I may purchase something with the same sort of costs as diamonds. The problem is one simply cannot research everything!

And in the law, ignorance is not an excuse.