Gold Coins of 1973
Sovereigns and half sovereigns were not issued in every year, and this is one date for which none were issued.
Very few countries issued any gold coins in 1973, however we can suggest some alternatives.
Alternative World Gold Coins

Country	Denomination	Diameter	Weight	Alloy	AGW	Cat
Bahamas	$200	28.5	10.9200	.9166	0.3219	$225
Bahamas	$150	24	8.1900	.9166	0.2414	$150
Bahamas	$100	27.5	14.5400	.750	0.3506	$180
Bahamas	$100	27.5	14.5400	.585	0.2735	$145
Bahamas	$50	29.5	15.6448	.500	0.2515	$100
Bahamas	$50	22	7.2700	.750	0.1753	$100
Bahamas	$50	22	7.2700	.585	0.1367	$85
Bahamas	$20	19.5	2.900	.750	0.0699	$50
Bahamas	$20	19.5	2.900	.585	0.0545	$50
Bahamas	$10	15	1.4500	.750	0.0349	$40
Bahamas	$10	15	1.4500	.585	0.0349	$40
Chile	100 Pesos	32	20.3397	.9000	.5886	$250
Colombia	2,000 Pesos	26	12.9000	.9000	.3733	$200
Colombia	1,500 Pesos	24	8.6000	.9000	.2488	$140
Colombia	1,000 Pesos	20	4.3000	.9000	.1244	$60
Egypt	5 Pounds	36	42.5000	.8750	1.1957	$400
Egypt	1 Pound	23	8.5000	.8750	0.2391	$150
Ghana	2 Pounds	29	15.9800	.9166	0.4711	$250
Haiti	1,000 Gourdes	32	14.5600	.9000	0.4213	$300
Haiti	500 Gourdes	24	7.2800	.9000	0.2106	$125
Haiti	200 Gourdes	17.5	2.9100	.9000	0.8420	$60
Haiti	100 Gourdes	14	1.4500	.9000	0.0419	$40
Isle of Man	5 Pounds	36	39.9500	.9166	1.2588	$500
Isle of Man	2 Pounds	29	15.9253	.9166	0.4695	$200
Isle of Man	Sovereign	22	7.9881	.9166	0.2355	$100
Isle of Man	Half Sovereign	19	3.98131	.9166	0.1173	$50
Isle of Man	Gold 4 Coin Proof & Mint Sets		67.6827	.9166	1.9947	$
Israel	200 Lirot	32	27.0000	.900	0.7813	$375
Israel	100 Lirot	26.5	13.5000	.900	0.3906	$200
Israel	50 Lirot	22	7.0000	.9000	0.2025	$150
Malta	£50	28	15.0000	.9166	0.4418	$200
Malta	£20	22	6.0000	.9166	0.1767	$80
Malta	£10	19	3.0000	.9166	0.0883	$40
Nepal	1 Rupee	27				$300
Nepal	Half Rupee					$150
Nepal	Quarter Rupee					$300
Paraguay	4500 Guaranies	40	31.9000	.9000	0.9231	$500
Paraguay	3000 Guaranies	33	21.3000	.9000	0.6164	$350
Paraguay	1500 Guaranies		10.7000	.9000	0.3096	$175
South Africa	One Ounce Krugerrand	32.7	33.93	.9166	1.00	Bullion
South Africa	2 Rand	22.05	7.9881	.9166	0.2354	$95
South Africa	1 Rand	19.30	3.9940	.9166	0.1177	$50

Key
Denomination = Face value
Diameter = Approximate Diameter in millimetres.
Weight = Weight in grams.
Alloy = Fineness of gold.
AGW = Actual fine gold weight in troy ounces.