To track the veracity and value of gold certificates, you must have knowledge of the physical gold market (as opposed to gold futures or gold mining investments) so that you can protect your investment. You might invest in gold because you view it as a safe store of value. However, without the ability to verify that a gold certificate is, in fact, backed by physical bullion, some of that value can be negated.
Verify that your certificate represents an allocated holding. While there are reputable issuers of gold certificates that don't allow daily audits of their vaults, such as the Perth Mint, an auditing system is the only way to truly track a gold certificate and its underlying value. If you're interested in tracking the certificate, it's important that an open, published audit of the holdings and the owners of the holdings is available to link a certificate to a unique piece of gold. Otherwise, there's the danger of counterfeit certificates diminishing the true value of the holding.
Locate the serial number on your certificate. Most reputable gold suppliers, such as Credit Suisse gold bars, brand each bar of gold produced with a serial number. The certificate of ownership accompanying that gold bar has an identical serial number printed on it; this serial number will allow you to match the certificate with a specific piece of gold.
Track the gold using the vault's auditing system. If you own a certificate for what's called allocated gold, you should be able to, at any time, either verify with a bank official or through an online system that a particular gold piece is in a vault and that the certificate is being held only by you, according to Bullion Vault, which publishes daily audits of their holdings by serial number.
It's possible to track the gold in unallocated holdings such as those of the Perth Mint by using a serial number. However, it's important to trust the reputation of that particular vault and, specifically, to trust that the company is not creating multiple certificates. This, in effect, means that the company is participating in fractional reserve banking, in which case you won't be able to track the certificate.