How does stock Ref/Id work on google finance?

AN8068571086 is the International Securities Identification Number (ISIN https://www.investopedia.com/terms/i/isin.asp) for SCHLUMBERGER N.V. (LTD.). An ISIN is an international symbol for a company's stocks which may be traded on multiple exchanges. If the shares are traded on multiple exchanges the ISIN will remain the same but a market code (such as a MIC) attached to the ISIN will change dependent on the market. ISIN also covers some other securities such as Fixed Income which are irrelevant here. Not all stocks have an ISIN.

The identifier used by Google finance "NYSE:SLB" is the market ticker code. This contains the name of the specific market, in this case NYSE, and the ticker code for that stock on that exchange. The ticker code is not universal so will be different on a market by market basis. To map between ISIN and ticker code you also need the details of the exchange on that you are interested in and where the stock is traded. Since the ticker code is not universal this will change wildly for some stocks, especially where the dual listing is as a result of a merger or an acquisition.

Google finance seems to have data for Swatch group under the ticker code "SWX:UHR", the reason you couldn't find it is likely that Google Finance doesn't link the ticker to the ISIN and the code doesn't look like the word swatch. Incidentally this is the ticker for Swatch on the Six Swiss exchange Swatch is also listed as "VTX:UHR" in some places where VTX is another code for SWX.

In general it is better to use ISIN + MIC to uniquely identify a stock and the particular exchange you are interested in rather than ticker code as the latter is not consistent and the former is a universal standard. In my professional life we ask all of our clients to provide ISIN + MIC unless the security doesn't have an ISIN since if the ticker and exchange code don't match it can be impossible to find the security. I once had to ring a trader to find out what a security was after our entire market data team shrugged and gave up.

Google finance is not the best source of data, particularly because it doesn't always have the ISIN, but I understand its uses as a free source of data. Finding the data is the true cost of it being "free"!