The notion that the labor theory of value says that the value of a commodity is the quantity of labor to produce it is a common misconception. What it actually says is that the value of a commodity is the socially necessary labor time to produce it. What this phrase refers to is the time it takes, under average work conditions, to produce a commodity. This is evident in reality; we see that capitalism is a system of competitive private firms that aim to produce commodities as quickly and cheaply as possible in order to out-compete rivals. If Mark takes a lot of time to produce the same commodity as Jill, Jill's commodity will sell better on the market because she produced it in less time, and therefore can sell it at a lower price than Mark.

A crucial point to remember is that the labor theory of value describes commodity production. So, no, you can't analyze a diamond you happen to come across nor water in a desert with the labor theory of value.

There are three aspects to the commodity:

• Use-value (or utility)

• Exchange-value (how much the commodity exchanges for, usually expressed in terms of money)

• Being sold by a capitalist for profit

There are many workers who meet some or all of these criteria. For example, a person who works in a toothbrush factory making toothbrushes, fulfills all three criteria. She produces use-values, exchange-values, and the finished product is taken by capitalists and sold on the market. Therefore, she produces Marxian value.

Then we have what are called unproductive laborers. Unproductive laborers produce use-values but not exchange-values and the fruits of their labor are not sold on the market by capitalists. Unproductive laborers include janitors, managers, security, and all other jobs whose occupants are not directly involved in the commodity production process but maintain the business in some other way.

For a really excellent book on what a future socialist society might look like, read Towards a New Socialism by Allin Cottrell and Paul Cockshott. In regards to a possible payment system in such a system, read the following excerpt from page 31 of the .pdf file:

The great merit of these original [socialist] principles is that they provide a coherent foundation for an entire system, not just of economic organisation, but also a whole new legal, moral and social order. They imply a monetary system based upon time rather than upon arbitrary and meaningless currency units like Pounds, Dollars or Ecu. People would be credited with hours worked rather than money at the end of the week. Payments for goods and services would also be in terms of time. You would pay for a garment that took two hours to produce with two hours of your own time. An economy based upon time-prices would have built into it the democratic presumption of human equality. Marx outlined the sort of system we have in mind as follows:

Accordingly, the individual producer gets back from society—after the deductions—exactly what he has given it. What he has given it is his individual quantum of labour. For instance, the social working day consists of the sum of the individual hours of work. The individual labour time of the individual producer thus constitutes his contribution to the social working day, his share of it. Society gives him a certificate stating that he has done such and such an amount of work (after the labour done for the communal fund has been deducted), and with this certificate he can withdraw from the social supply of means of consumption as much as costs an equivalent amount of labour. The same amount of labour he has given to society in one form, he receives back in another. (Marx, 1974, p. 346)

Note that these certificates of labour performed are quite distinct from money. They can only be obtained by labour and can only be exchanged against consumer goods. In another passage Marx argues that Robert Owen’s so-called ‘labour money’ was not money at all:

On this point I will only say that Owen’s ‘labour money’, for instance, is no more ‘money’ than a theatre ticket is. Owen presupposes directly socialized labour, a form of production diametrically opposed to the production of commodities. The certificate of labour is merely evidence of the part taken by the individual in the common labour, and of his claim to a certain portion of the common product which has been set aside for consumption. But Owen never made the mistake of presupposing the production of commodities, while, at the same time, by juggling with money, trying to circumvent the necessary conditions of that form of production. (Marx, 1976, pp. 188–9)

When Marx says that labour certificates are no more money than a theatre ticket we can draw certain implications:

(1) The certificates do not circulate; they can only be directly exchanged against consumer goods.

(2) Like many tickets they would be non-transferable. Only the person who had performed the labour could use them.

(3) They would be cancelled after a single use, just as a theatre ticket is destroyed on entry to the theatre. When individuals withdrew goods from a shop their vouchers would be cancelled. The shop, as a communal organisation, has no need to buy in goods, it is just allocated them, so its only interest in the labour vouchers is for record-keeping purposes.

(4) They would not serve as a store of value. They could have a ‘use by’ date on them. Unless individuals redeemed their share of this year’s output by the end of the year, it would be assumed that they did not want it. If labour tokens are not spent then the goods that embodied the labour would not be used. Many goods are perishable and they would have to be disposed of somehow.

Nowadays one need not think in terms of paper certificates of work done. Instead we can envisage the use of some form of labour credit card which keeps track of how much work you have done. Deductions from your social labour credit account could be made by filling in a slip, or using a direct debit terminal.

We are presented by Marx with a model—a skeletal one but a clear one— of a socialist society in which there are no commodities (i.e. goods produced specifically for exchange on a market). People are paid in labour credits for work done. Deductions are made for communal needs. Goods are distributed on the basis of their labour content, with corresponding deductions from people’s credit accounts. Production is organised on a directly social basis with intermediate products never assuming the form of commodities.

Essentially, how much a worker would be paid in the socialist labor voucher system is determined by the quantity of their work, and likely the quality of it, too. If a worker contributes eight hours of labor time, they'd get compensated in full for those eight hours.