Big gold religious coin

I have a large gold coin, that is a commemorative coin of Don Bosco. The coin is recognizing the 100 years of his followers the Saleians. You can see pictures I posted. But my question is this, one., is the coin real gold? I have done every online gold test and every single one passes as gold. Without question. The bing, the vinegar, the not floating on water, fire, and so on. I brought it to a gold buyer, and they said it was not real, but were suspicious in their actions. They wouldn’t show me the gold analysis results, and one of them said it was certain elements, and another one said different elements. And they have been very off before in the business the conduct. I did see there is a pure gold commemoration coin  that marks the 150 year anniversary, but it is much smaller as it was 1.2 grams and mine is 300! Please advise of any information about this coin. 
thanks

Your medal does not look to be made of gold based on the images you sent

Parece me um medalha de bronze, com banho de ouro, para o peso de 300 gramas 

Enrico Manfrini  is well known to manufacture large 60mm bronze religious medals.

For such a huge medal a precise calculation (and/or measurement) of the volume would lead to a smaller density than gold.

Then your medal has certainly been gold plated like this one